Relationships between specialized cells, capillaries and intermediary cytofibrillary elements. XVIIth Note. Biological evolution of the respiratory subsystem in Reptilia.

This note continues the XIIth, XVth and XVIth ones concerning the biological evolution of the respiratory subsystem (SS.Rs.) in invertebrates, aquatic vertebrates and amphibians. Author tries to discern some of the factors involved in the passage from Amphibia to Reptilia. The lengthy evolution of embryotrophic mechanisms during this process in the light of the aromorphotic theory (A. N. Sewertsow) and the accelerating form of dyschronism (De Beer) are highlighted. The result of these changes is the formation of a large telolecithal egg endowed with all the embryotrophic reserves needed for the terrestrial evolution, for its acceleration and condensation, through the suppression of the larval stage and of metamorphosis, as well as through the appearance of some new characters. The evolution of the extraembryonic area in Amniota precursors and in Amniota and their homeothermal descendants, both oviparous and viviparous, is also discussed. The succession of respiratory organs is followed up (yolk sac, external branchiae, allantois, placenta) in the light of the organ substitution theory and of the biological stereo-type theory (Mârza, Repciuc, Eskenasy).