VASCULARIZATION IN THE BRAINS OF REPTILES V. NOTES ON SOME SNAKES AND LIZARDS

Resumen

1. The total length of the capillaries in a unit volume of tissue in each of twenty-two regions of the brain has been measured in four snakes and in four lizards (Anolis). The fundamental difference in the morphology of the vessels in lizards, which have branched, non-anastomosing loops instead of the spongy capillary network of most animals, has not been considered in making this quantitative study.
2. The lengths of the capillaries in snakes are generally comparable with those in alligator and turtle though lending to be a little greater. They are definitely greater in lizards in most parts of the brain studied.
3. The cochlear nucleus is particularly well supplied with capillaries, especially in the snakes, and the hypoglossal nucleus also is notably richer in snakes and lizards than in the other reptiles. The cerebellum is also relatively highly vascular in the lizards.
4. The calibre of the capillaries is slightly greater in the snakes than in the lizard but is less than in the young alligator or the small turtle previously studied.
5. The areas of the walls of the capillaries and the volumes of these vessels show no consistent differences. The area over which a unit volume of blood is spread is about the same in the snakes and alligators, apparently a little greater in the lizards.