Читать книгу Histology of the Blood, Normal and Pathological - Paul Ehrlich - Страница 4

Table of Contents

In practical medicine the term "anæmia" has not quite the restricted sense that scientific investigation gives it. The former regards certain striking symptoms as characteristic of the anæmic condition; pallor of the skin, a diminution of the normal redness of the mucous membranes of the eyes, lips, mouth, and pharynx. From the presence of these phenomena anæmia is diagnosed, and according to their greater or less intensity, conclusions are also drawn as to the degree of the poverty of the blood.

It is evident from the first that a definition based on such a frequent and elementary chain of symptoms will bring into line much that is unconnected, and will perhaps omit what it should logically include. Indeed a number of obscurities and contradictions is to be ascribed to this circumstance.

The first task therefore of a scientific treatment of the anæmic condition is carefully to define its extent. For this purpose the symptoms above mentioned are little suited, however great, in their proper place, their practical importance may be.

Etymologically the word "anæmia" signifies a want of the normal quantity of blood. This may be "general" and affect the whole organism; or "local" and limited to a particular region or a single organ. The local anæmias we can at once exclude from our consideration.

A priori, the amount of blood may be subnormal in two senses, quantitative and qualitative. We may have a diminution of the amount of blood—"Oligæmia." Deterioration of the quality of the blood may be quite independent of the amount of blood, and must primarily express itself in a diminution of the physiologically important constituents. Hence we distinguish the following chief types of alteration of the blood; (1) diminution of the amount of Hæmoglobin (Oligochromæmia), and (2) diminution of the number of red blood corpuscles (Oligocythæmia).

We regard as anæmic all conditions of the blood where a diminution of the amount of hæmoglobin can be recognised; in by far the greater number of cases, if not in all, Oligæmia and Oligocythæmia to a greater or less extent occur simultaneously.

The most important methods of clinical hæmatology bear directly or indirectly on the recognition of these conditions.

There is at present no method of estimation of the total quantity of the blood which can be used clinically. We rely to a certain extent on the observation of the already mentioned symptoms of redness or pallor of the skin and mucous membranes. To a large degree these depend upon the composition of the blood, and not upon the fulness of the peripheral vessels. If we take the latter as a measure of the total amount of blood, isolated vessels, visible to the naked eye, e.g. those of the sclerotic, may be observed. Most suitable is the ophthalmoscopic examination of the width of the vessels at the back of the eye. Ræhlmann has shewn that in 60% of the cases of chronic anæmia, in which the skin and mucous membranes are very white, there is hyperæmia of the retina—which is evidence that in such cases the circulating blood is pale in colour, but certainly not less in quantity than normally. The condition of the pulse is an important indication of diminution of the quantity of the blood, though only when it is marked. It presents a peculiar smallness and feebleness in all cases of severe oligæmia.

The bleeding from fresh skin punctures gives a further criterion of the quantity of blood, within certain limits, but is modified by changes in the coagulability of the blood. Anyone who has made frequent blood examinations will have observed that in this respect extraordinary variations occur. In some cases scarcely a drop of blood can be obtained, while in others the blood flows freely. One will not err in assuming in the former case a diminution of the quantity of the blood.

The fulness of the peripheral vessels however is a sign of only relative value, for the amount of blood in the internal organs may be very different. The problem, how to estimate exactly, if possible mathematically, the quantity of blood in the body has always been recognised as important, and its solution would constitute a real advance. The methods which have so far been proposed for clinical purposes originate from Tarchanoff. He suggested that one may estimate the quantity of blood by comparing the numbers of the red blood corpuscles before and after copious sweating. Apart from various theoretical considerations this method is far too clumsy for practical purposes.

Quincke has endeavoured to calculate the amount of blood in cases of blood transfusion for therapeutic purposes. From the number of red blood corpuscles of the patient before and after blood transfusion, the amount of blood transfused and the number of corpuscles it contains, by a simple mathematical formula the quantity of the blood of the patient can be estimated. But this method is only practicable in special cases and is open to several theoretical errors. First, it depends upon the relative number of red blood corpuscles in the blood; inasmuch as the transfusion of normal blood into normal blood, for example, would produce no alteration in the count. This consideration is enough to shew that this proceeding can only be used in special cases. It has indeed been found that an increase of the red corpuscles per cubic millimetre occurs in persons with a very small number of red corpuscles, who have been injected with normal blood. But it is very hazardous to try to estimate therefrom the volume of the pre-existing blood, since the act of transfusion undoubtedly is immediately followed by compensatory currents and alterations in the distribution of the blood.

No property of the blood has been so exactly and frequently tested as the number of red corpuscles per cubic millimetre of blood. The convenience of the counting apparatus, and the apparently absolute measure of the result have ensured for the methods of enumeration an early clinical application.

At the present time the instruments of Thoma-Zeiss or others similarly constructed are generally used; and we may assume that the principle on which they depend and the methods of their use are known. A number of fluids are used to dilute the blood, which on the whole fulfil the requirements of preserving the form and colour of the red corpuscles, of preventing their fusing together, and of allowing them to settle rapidly. Of the better known solutions we will here mention Pacini's and Hayem's fluids.

Pacini's solution.	Hydrarg. bichlor.	2.0
	Natr. chlor.	4.0
	Glycerin	26.0
	Aquæ destillat.	226.0
Hayem's solution.	Hydrarg. bichlor.	0.5
	Natr. sulph.	5.0
	Natr. chlor.	1.0
	Aquæ destillat.	200.0

For counting the white blood corpuscles the same instrument is generally used, but the blood is diluted 10 times instead of 100 times. It is advantageous to use a diluting fluid which destroys the red blood corpuscles, but which brings out the nuclei of the white corpuscles, so that the latter are more easily recognised. For this purpose the solution recommended by Thoma is the best—namely a half per cent. solution of acetic acid, to which a trace of methyl violet has been added[1].

The results of these methods of enumeration are sufficiently exact, as they have, according to the frequently confirmed observations of R. Thoma and I. F. Lyon, only a small error. In a count of 200 cells it is five per cent., of 1250 two per cent., of 5000 one, and of 20,000 one-half per cent.

There are certain factors in the practical application of these methods, which in other directions influence the result unfavourably.

It has been found by Cohnstein and Zuntz and others that the blood in the large vessels has a constant composition, but that in the small vessels and capillaries the formed elements may vary considerably in number, though the blood is in other respects normal. Thus, for example, in a one-sided paralytic, the capillary blood is different on the two sides; and congestion, cold, and so forth raise the number of red blood corpuscles. Hence, for purposes of enumeration, the rule is to take blood only from those parts of the body which are free from accidental variation; to avoid all influences such as energetic rubbing or scrubbing, etc., which alter the circulation in the capillaries; to undertake the examination at such times when the number of red blood corpuscles is not influenced by the taking of food or medicine.

It is usual to take the blood from the tip of the finger, and only in exceptional cases, e.g. in œdema of the finger, are other places chosen, such as the lobule of the ear, or (in the case of children) the big toe. For the puncture pointed needles or specially constructed instruments, open or shielded lancets, are unnecessary: we recommend a fine steel pen, of which one nib has been broken off. It is easily disinfected by heating to redness, and produces not a puncture but what is more useful, a cut, from which blood freely flows without any great pressure.

The literature dealing with the numbers of the red corpuscles in health, is so large as to be quite unsurveyable. According to the new and complete compilation of Reinert and v. Limbeck, the following figures (calculated roundly for mm.³) may be taken as physiological:

Men.
Maximum	Minimum	Average
7,000,000	4,000,000	5,000,000
Women.
Maximum	Minimum	Average
5,250,000	4,500,000	4,500,000

This difference between the sexes first makes its appearance at the time of puberty of the female. Up to the commencement of menstruation the number of corpuscles in the female is in fact slightly higher than in the male (Stierlin). Apart from this, the time of life seems to cause a difference in the number of red corpuscles only in so far that in the newly-born, polycythæmia (up to 8–½ millions during the first days of life) is observed (E. Schiff). After the first occasion on which food is taken a decrease can be observed, and gradually (though by stages) the normal figure is reached in from 10–14 days. On the other hand the oligocythæmia here and there observed in old age, according to Schmaltz, is not constant, and therefore cannot be regarded as a peculiarity of senility, but must be caused by subsidiary processes of various kinds which come into play at this stage of life.

The influence which the taking of food exercises on the number of the red blood corpuscles is to be ascribed to the taking in of water, and is so insignificant, that the variations, in part at least, fall within the errors of the methods of enumeration.

Other physiological factors: menstruation (that is, the single occurrence), pregnancy, lactation, do not alter the number of blood corpuscles to any appreciable extent. The numbers do not differ in arterial and venous blood.

All these physiological variations in the number of the blood corpuscles, are dependent, according to Cohnstein and Zuntz, on vasomotor influences. Stimuli, which narrow the peripheral vessels, locally diminish the number of red blood corpuscles; excitation of the vasodilators brings about the opposite effect. Hence it follows, that the normal variations of the number contained in a unit of space are merely the expressions of an altered distribution of the red elements within the circulation, and are quite independent of the reproduction and decay of the cells.

Climatic conditions apparently exercise a great influence over the number of corpuscles. This fact is important for physiology, pathology, and therapeutics, and has come to the front especially in the last few years, since Viault's researches in the heights of the Corderillas. As his researches, as well as those of Mercier, Egger, Wolff, Kœppe, v. Jaruntowski and Schrœder, Miescher, Kündig and others, shew, the number of red blood corpuscles in a healthy man, with the normal average of 5,000,000 per mm.³, begins to rise immediately after reaching a height considerably above the sea-level. With a rise proceeding by stages, a new average figure is reached in 10 to 14 days, considerably larger than the old one, and indeed the greater the difference in level between the former and the latter places, the greater is the difference in this figure. Healthy persons born and bred at these heights have an average of red corpuscles which is considerably above the mean; and which indeed as a rule is somewhat greater than in those who are acclimatised or only temporarily living at these elevations.

The following small table gives an idea of the degree to which the number of blood corpuscles may vary at higher altitudes from the average of five millions.

Author	Locality	Height above sea-level	Increase of
v. Jaruntowski	Görbersdorf	561 metres	800,000
Wolff and Kœppe	Reiboldsgrün	700 "	1,000,000
Egger	Arosa	1800 "	2,000,000
Viault	Corderillas	4392 "	3,000,000

Exactly the opposite process is to be observed when a person accustomed to a high altitude reaches a lower one. Under these conditions the correspondingly lower physiological average is produced. These interesting processes have given rise to various interpretations and hypotheses. On the one hand, the diminished oxygen tension in the upper air was regarded as the immediate cause of the increase of red blood corpuscles. Miescher, particularly, has described the want of oxygen as a specific stimulus to the production of erythrocytes. Apart from the physiological improbability of such a rapid and comprehensive fresh production, one must further dissent from this interpretation, since the histological appearance of the blood gives it no support. Kœppe, who has specially directed part of his researches to the morphological phenomena produced during acclimatisation to high altitudes, has shewn, that in the increase of the number of red corpuscles two mutually independent and distinct processes are to be distinguished. He observed that, although the number of red corpuscles was raised so soon as a few hours after arrival at Reiboldsgrün, numerous poikilocytes and microcytes make their appearance at the same time. The initial increase is therefore to be explained by budding and division of the red corpuscles already present in the circulating blood. Kœppe sees in this process, borrowing Ehrlich's conception of poikilocytosis, a physiological adaptation to the lower atmospheric pressure, and the resulting greater difficulty of oxygen absorption. The impediment to the function of the hæmoglobin is to a certain extent compensated, since the stock of hæmoglobin possesses a larger surface, and so is capable of increased respiration. So also the remarkable fact may be readily understood that the sudden rise of the number of corpuscles is not at first accompanied by a rise of the quantity of hæmoglobin, or of the total volume of the red blood corpuscles. These values are first increased when the second process, an increased fresh production of normal red discs, takes place, which naturally requires for its developement a longer time. The poikilocytes and microcytes then vanish, according to the extent of the reproduction; and finally a blood is formed, which is characterised by an increased number of red corpuscles, and a corresponding rise in the quantity of hæmoglobin, and in the percentage volume of the corpuscles.

Other authors infer a relative and not an absolute increase in the number of red corpuscles. E. Grawitz, for example, has expressed the opinion that the raised count of corpuscles may be explained chiefly by increased concentration of the blood, due to the greater loss of water from the body at these altitudes. The blood of laboratory animals which Grawitz allowed to live in correspondingly rarefied air underwent similar changes. Von Limbeck, as well as Schumburg and Zuntz, object to this explanation on the ground, that if loss of water caused such considerable elevations in the number, we should observe a corresponding diminution in the body weight, which is by no means the case.

Schumburg and Zuntz also regard the increase of red blood corpuscles in the higher mountains as relative only, but explain it by an altered distribution of the corpuscular elements within the vascular system. In their earlier work Cohnstein and Zuntz had already established that the number of corpuscles in the capillary blood varies with the width of the vessels and the rate of flow in them. If one reflects how multifarious are the merely physiological influences at the bottom of which these two factors lie, one will not interpret alterations in the number of the red corpuscles without bearing them in mind. In residence at high altitudes various factors bring about alterations in the width of the vessels and in the circulation. Amongst these are the intenser light (Fülles), the lowering of temperature, increased muscular exertion, raised respiratory activity. Doubtless, therefore, without either production of microcytes or production de novo, the number of red corpuscles in capillary blood may undergo considerable variations.

The opposition, in which as mentioned above, the views of Grawitz, Zuntz, and Schumburg stand to those of the first mentioned authors, finds its solution in the fact that the causes of altered distribution of the blood, and of loss of water, play a large part in the sudden changes. The longer the sojourn however at these great elevations, the more insignificant they become (Viault).

We think therefore that from the material before us we may draw the conclusion, that after long residence in elevated districts the number of red blood corpuscles is absolutely raised. The therapeutic importance of this influence is obvious.

Besides high altitudes, the influence of the tropics on the composition of the blood and especially on the number of corpuscles has also been tested. Eykmann as well as Glogner found no deviation from the normal, although the almost constant pallor of the European in the tropics points in that direction. Here also, changes in the distribution occurring without qualitative changes of the blood seem chiefly concerned.

The same reliance cannot be placed on inferences based on the results of the Thoma-Zeiss and similar counting methods for anæmic as for normal blood, in which generally speaking all the red cells are of the same size and contain the same amount of hæmoglobin. In the former the red corpuscles, as we shall shew later, differ considerably one from another. On the one hand forms poor in hæmoglobin, on the other very small forms occur, which by the wet method of counting cannot even be seen.

Apart even from these extreme forms, 1,000 red blood corpuscles of anæmic blood are not physiologically equivalent to the same number of normal blood corpuscles. Hence the necessity of closely correlating the result of the count of red blood corpuscles with the hæmoglobinometric and histological values. The first figure only, given apart from the latter, is often misleading, especially in pathological cases.

It is therefore occasionally desirable to supplement the data of the count by the estimation of the size of the red blood corpuscles individually. This is effected by direct measurement with the ocular micrometer; and can be performed on wet (see below), as well as on dry preparations, though the latter in general are to be preferred on account of their far greater convenience.

Nevertheless the carrying out of this method requires particular care. One can easily see that in normal blood the red corpuscles appear smaller in the thicker than they do in the thinner layers of the dry preparation. We may explain this difference as follows. In the thick layers the red discs float in plasma before drying, whilst in the thinner parts they are fastened to the glass by a capillary layer. Desiccation occurs here nearly instantaneously, and starts from the periphery of the disc; so that an alteration in the shape or size is impossible. On the contrary the process of drying in the thicker portions proceeds more slowly, and is therefore accompanied by a shrinking of the discs.

Even in healthy persons small differences in the individual discs are shewn by this method. The physiological average of the diameter of the greater surface is, according to Laache, Hayem, Schumann and others, 8.5 µ for men and women (max. 9.0 µ. min. 6.5 µ.) In anæmic blood the differences between the individual elements become greater, so that to obtain the average value, the maxima, minima, and mean of a large number of cells, chosen at random, are ascertained. But with a high degree of inequality of the discs this microscopical measurement loses all scientific value.

However valuable the knowledge of the absolute number may be for a judgment on the course of the illness, it gives us no information about the amount of hæmoglobin in the blood, which is the decisive measure of the degree of the anæmia. A number of clinical methods are in use for this estimation; first direct, such as the colorimetric estimation of the amount of hæmoglobin, secondly indirect, such as the determination of the specific gravity or of the volume of the red corpuscles, and perhaps also the estimation of the dry substance of the total blood.

Among the direct methods for hæmoglobin estimation, which aim at the measurement of the depth of colour of the blood, we wish first to mention one, which though it lays no claim to great clinical accuracy has often done us good service as a rapid indicator at the bedside. A little blood is caught on a piece of linen or filter-paper, and allowed to distribute itself in a thin layer. In this manner one can recognise the difference between the colour of anæmic and of healthy blood more clearly than in the drop as it comes from the finger prick. After a few trials one can in this way draw conclusions as to the degree of the existing anæmia. Could this simple method which is so convenient, which can be carried out at the time of consultation, come more into vogue, it alone would contribute to the decline of the favourite stop-gap diagnosis, 'anæmia.' For neurasthenic patients also, who so often fancy themselves anæmic and in addition look so, a demonstratio ad oculos such as this is often sufficient to persuade them of the contrary.

Of the instruments for measuring the depth of colour of the blood, the double pipette of Hoppe-Seyler is quite the most delicate. A solution of carbonic oxide hæmoglobin, accurately titrated, serves as the standard of comparison. The reliable preparation and conservation of the normal solution is however attended with such difficulties, that this method is not clinically available. In the last few years, Langemeister, a pupil of Kühne's, has invented a method for colorimetric purposes, also applicable to hæmoglobin estimations. The instrument depends on the principle, that from the thickness of the layer in which the solution to be tested has the same colour intensity as a normal solution, the amount of colour can be calculated. As a normal solution Langemeister uses a glycerine solution of methæmoglobin prepared from pig's blood. To our knowledge this method has not yet been applied clinically. Its introduction would be valuable, for in practice we must at present be content with methods that are less exact, in which coloured glass or a stable coloured solution serves as a measure for the depth of colour of the blood. There are a number of instruments of this kind, of which the "hæmometer" of Fleischl, and amongst others, the "hæmoglobinometer" of Gowers, distinguished by its low price, are specially used for clinical purposes. Both instruments give the percentage of the hæmoglobin of normal blood which the blood examined contains, and are sufficiently exact in their results for practical purposes and for relative values; although errors up to 10% and over occur with unpractised observers. (Cp. K. H. Mayer.) Quite recently Biernacki has raised the objection to the colorimetric methods of the quantitative estimation of hæmoglobin, that the depth of colour of the blood is dependent not only on the quantity of hæmoglobin but also on the colour of the plasma, and the greater or less amount of proteid in the blood. These errors are quite inconsiderable for the above-mentioned instruments, since here the blood is so highly diluted with water that the possible original differences are thereby reduced to zero.

Among the methods for indirect hæmoglobin estimation, that of calculation from the amount of iron in the blood appears to be quite exact, since hæmoglobin possesses a constant quantity of iron of 0.42 per cent. This calculation may be allowed in all cases for normal blood, for here there is a really exact proportion between the amounts of hæmoglobin and of iron. Recently A. Jolles has described an apparatus for quantitative estimation of the iron of the blood, called a "ferrometer;" which renders possible an accurate valuation of the iron in small amounts of blood. However for pathological cases this method of hæmoglobin estimation from the iron present is not to be recommended. For if one tests the blood of an anæmic patient under the microscope for iron one finds the iron reaction in numerous red blood corpuscles. This means the presence of iron which is not a normal constituent of hæmoglobin. Other iron may be contained in the morphological elements (including the white corpuscles) as a combination of proteid with iron, which is not directly recognisable. It is further known that in anæmias the amount of iron of all organs is greatly raised (Quincke), apparently often the result of a raised destruction of hæmoglobin ("waste iron," "spodogenous iron"). In many cases too, it should be borne in mind that the administration of iron increases the amount of iron in the blood and organs.

From these considerations we see how unreliable in pathological cases is the calculation of the amount of hæmoglobin from the amount of iron. We have been particularly led to these observations by the work of Biernacki, since the procedure of inferring the amount of hæmoglobin from the amount of iron has led to really remarkable conclusions. For example, amongst other things, he found the iron in two cases of mild, and one of severe chlorosis quite normal. He concludes that chlorosis, and other anæmias, shew no diminution, but even a relative increase of hæmoglobin: but that other proteids of the blood on the contrary are reduced. These difficult iron estimations stand out very sharply from the results of other authors and could only be accepted after the most careful confirmation. But the above analysis shews, that in any case the far-reaching conclusions which Biernacki has attached to his results are insecure. For these questions especially, complete estimations with the aid of the ferrometer of A. Jolles are to be desired.

Great importance has always been attached to the investigation of the specific gravity of the blood; since the density of the blood affords a measure of the number of corpuscles, and of their hæmoglobin equivalent. It is easy to collect observations, as in the last few years two methods have come into use which require only a small quantity of material, and do not appear to be too complicated for practical clinical purposes. One of these has been worked out by R. Schmaltz, in which small amounts of blood are exactly weighed in capillary glass tubes (the capillary pyknometric method). The other is A. Hammerschlag's, in which, by a variation of a principle which was first invented by Fano, that mixture of chloroform and benzol is ascertained in which the blood to be examined floats, i.e. which possesses exactly the specific gravity of the blood[2].

According to the researches of these authors and numerous others who have used their own methods, the specific gravity of the total blood is physiologically 1058–1062, or on the average 1059 (1056 in women). The specific gravity of the serum amounts to 1029–1032—on the average 1030. From which it at once follows that the red corpuscles must be the chief cause of the great weight of the blood. If their number diminishes, or their number remaining constant, they lose in hæmoglobin, or in volume, the specific gravity would be correspondingly lowered. We should therefore expect a low specific gravity in all anæmic conditions. Similarly with an increased number of corpuscles, and a high hæmoglobin equivalent, an increase in the density of the total blood makes its appearance.

Hammerschlag has found in a large number of experiments that the relation between the specific gravity and the amount of hæmoglobin is much closer than between the specific gravity and the number of corpuscles. The former in fact is so constant that it may be represented by a table.