The most interesting of Shchurovskii 's postulates starts 

 with the confirmation that all lower animals are analogous to 

 the egg. Just as the formation of an organism is included in 

 the egg, so in the lower animals "the possible development of 

 the animal kingdom, for reasons not yet discovered, is 

 included in the formation of the organs, Therefore in infusoria, 

 polyps, and zoophytes, the ideas of the heart and other organs 

 have not yet materialized," Shchurovskii assumed that the 

 heart was first formed in insects, where it has the shape of 

 an elongated unbranched vessel and is analogous to the heart 

 of the chick embryo twenty-seven hours after fertilization. 

 In spiders and annelids (annulated worms) , arteries and veins 

 appear. "This second stage of development corresponds with the 

 thirty-first hour after fertilization" (p. 199). 



If in insects (first stage) the heart extends in a 

 straight line, and if in the second stage it is stretched in 

 its surface, then in the third stage, to which Shchurovskii 

 related the molluscs, the heart "merges and closes up in a 

 sphere." In "shell" molluscs it forms two widenings, "of which 

 one (the auricle) . . . receives the veins, and the other 

 (the ventricle) returns the arterial blood to all the body" 

 (p. 200). Molluscs are thus analogous to the chick embryo in 

 the thirty-sixth hour after fertilization. Shchurovskii 

 located the heart of the cephalopod molluscs between the third 

 and fourth stages, noting that, for example, in the cuttlefish 

 there are three muscular widenings, to which correspond, in 

 the more highly organized animals, the auricle, ventricle, and 

 the descending aorta. Similarly, the hearts of fish correspond 

 with the fourth stage of development of the bird embryo, i.e. 

 to the forty-eighth hour after fertilization. 



The heart of the lower reptiles (i.e. amphibia) is similar 

 to the heart of fish, according to Shchurovskii. As "in 

 tortoises, snakes, and lizards, which are considered of a 

 higher class, it takes a special form of development .... 

 The reptilian heart is of two-auricle, one-ventricle structure. 

 This fifth stage of development corresponds to the fifty-eighth 

 hour after fertilization, but with the difference that the 

 duplication of the ventricle in birds precedes the duplication 

 of the auricle" (p. 202). This stipulation interfered with the 

 harmony of the postulate and is, as was mentioned before > a 

 result of the mistaken description of the development of the 

 chick heart. 



187 



