Читать книгу Intelligence in Plants and Animals - Thomas G. Gentry - Страница 17

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That aphides secrete, or rather excrete, a saccharine fluid, called honey-dew, which constitutes an important part of the food of ants, is a fact well known to naturalists. It must not be supposed, however, that this was its primitive use. But that it is in some way connected with the preservation of the tender creatures by which it is elaborated, there can exist not the slightest doubt.

Concerning its origin and application, and the benefit which it secures to its authors, various opinions have been hazarded, but they have all been too unsatisfactory to merit more than a passing notice. That it was of some advantage to young aphides was surmised by many, but the proofs necessary to sustain such a surmise were unfortunately wanting. It was left to the latter half of the nineteenth century to throw correct light upon the subject.

Whilst engaged some few years ago in the study of the species that affects the blossoms of one of our gourds—the Cucurbita ovifera of botanists—certain phenomena were observed, which promised an easy and speedy solution of the problem.

Gathered in compact masses, like companies of soldiery preparing for a foray, hundreds of aphides were seen, busily feeding, all over the flowers. There were old and young, not an indiscriminate mingling of ages and sizes, but an orderly arrangement of families, each family preceded by its own appropriate head. First came the very young of each family, only to be followed by those that were older, leaving the oldest of all to lead up the rear.

BLOSSOM OF CUCURBITA.

Mother-Aphis and Her Army of Children on Tube.

Here, it was apparent, was a most wonderful manifestation of intelligent design. The newly-born, needing the mother’s earliest attention, were in closest proximity, while the almost mature were the farthest removed from her essential presence.

All this seemed to indicate the dearest relationship subsisting between mother and offspring, but judging from outward appearances, little, if any, love existed. It is true that maternal instinct, which is seldom so far gone as to shut its ears to the beseechings of suffering offspring for food, was far from being absent. Instances of its presence were momentarily noted.

But a stimulus seemed, in some cases, quite necessary to its manifestation. There were times when the honey-glands acted without any provocation. It was only, however, when the very tender were a-hungry, that pressure was brought to bear upon the mothers. A few gentle reminders served to arouse them from the apathetic indifference which possessed them. The antennæ of the young were the means employed for this purpose. Two or three caresses almost immediately brought a discharge of honey. Again and again was the process observed, and always with the same invariable result.

Never for a longer period than two days were the very young dependent upon this manner of feeding, for their digestive organs were too weak and delicate to assimilate earlier, without injury, the powerful juices of the food-plant.

But what of the older offspring? That they were far from being disregarded by parental provision, subsequent developments only too plainly showed. The excretion, though less urgent in their case than in that of the very young, was quite as indispensable. Were it not so, what reason can be assigned for their very strict adherence to the course over which the maternal head had already passed in feeding?

From what has been said, there can be no doubt that the newly-born aphis derives material advantage from the excretion. But as the supply is clearly above the requirements, why the excess? It is evident nature does not need it as a kind of compensation for losses sustained through aphides. Then what purpose does it serve? It becomes in part the pabulum of the stronger of the young, and this it accomplishes by mixing with the natural juices of the plant, thereby rendering them fit for use.

To serve as food for the young is then the primary object of aphis-excretion. That a secondary purpose, namely, the preservation of the species, is also subserved, there can be no question. How this is effected, it shall now be my endeavor to show.

Ants, it is well known, are fond of sugar, gums and saccharine solutions, as well as the rich juices and tender tissues of animals. But their appetite for sweets is stronger than for all other diets. To them aphis would prove quite as toothsome a morsel as it is to Coccinella, and would be as eagerly hunted for by them were it not for this matter of sweets.

Way back in the history of time, things were perhaps different from what they are now. Aphis was then a racy tidbit, and shared, no doubt, the murderous assaults of Formica, as it did of other carnivores.

For ages this may have been going on, but how long conjecture only can tell. But there came a time when affairs were changed. A new order of things was initiated. Earth was growing better and impressing new features upon its life. An Ant, more wise than any of its fellows, or any that had ever lived before, doubtless stepped upon the scene, and a new era for Aphis inaugurated.

Finding by accident, or otherwise, the delightful qualities of aphis-excretion, it would not be slow to communicate the information to its companions. And as news travels rapidly, and ants are by no means reticent creatures, but a short time would be necessary to carry it everywhere, till all the families, near and remote, of the great world of the Formicidæ would be made acquainted with the important discovery.

Now, as ants are endowed with a high degree of intelligence, considering the position they occupy in the grand scale of created existences, they would soon perceive that their highest good would be attained by taking under their protection the little creatures which are the authors of this excretion. From this time the ants would begin to abandon their sanguinary propensities and manifest some regard for the aphides. The latter, in return, perceiving the former’s friendly disposition, would cease to fear them, and learn to cater to their wants. Thus would be developed, in time, those amicable relations which subsist between the two great, yet widely differentiated, families.