Читать книгу The Circle of Knowledge: A Classified, Simplified, Visualized Book of Answers - Various - Страница 281

The heart is four-chambered, as in mammals and birds, and not three-chambered, as in other reptiles and amphibia. The pure and impure blood do not, therefore, mix inside the heart; but as such blending takes place outside, owing to imperfect separation of the great vessels, the net result is much the same as in the lizards.