ABSTRACT
This chapter presents a comparative study of the organs of various animals, and considers whether the evolutionary explanation of the structures does not involve too many absurdities to make it possible for us longer to tolerate such an explanation of their origin. The placental method of reproduction, by which the blood of the developing foetus is placed in the intimate and nutritive relation with the blood of the mother, is another very remarkable structure which is found in the certain sharks, as well as in the true mammals. In the case the opening of the oesophagus is constricted and almost closed for the time that this incubation goes on, while the mouth and the pharynx are greatly enlarged so as to form a spacious brood-pouch. The same structure and habits are also recorded for a different species in South America.
