THE EMBRYOLOGY OF THE SOUL. 147 



soul, we must lay special stress on the injunction to 

 keep both sides of it critically before us. For, in the 

 case of man, just as in all the higher animals and 

 plants, such appreciable perturbations of type (or 

 cenogeneses) have taken place during the millions of 

 years of development that the original simple idea of 

 palingenesis, or " epitome of history," has been greatly 

 disturbed and altered. While, on the one side, the 

 paling enetic recapitulation is preserved by the laws of 

 like-time and like-place heredity, it is subject to an 

 essential cenogenetic change, on the other hand, by 

 the laws of abbreviated and simplified heredity. That 

 is clearly seen in the embryonic evolution of the 

 psychic organs, the nervous system, the muscles, and the 

 sense-organs. But it applies in just the same manner 

 to the psychic functions, which are absolutely depen- 

 dent on the normal construction of these organs. 

 Their evolution is subject to great cenogenetic modifi- 

 cation in man and all other viviparous animals, 

 precisely because the complete development of the 

 embryo occupies a longer time within the body of the 

 mother. But we have to distinguish two periods of 

 individual psychogeny : (1) the embryonic, and (2) the 

 post- embryonic development of the soul. 



1. Embryonic Psychogeny. — The human foetus, or 

 embryo, normally takes nine months (or 270 days) to 

 develop in the uterus. During this time it is entirely 

 cut off from the outer world, and protected, not only 

 by the thick muscular wall of the womb, but also by 

 the special foetal membranes {embryolemmata) which 

 are common to all the three higher classes of verte- 

 brates — reptiles, birds, and mammals. In all the 

 classes of amniotes these membranes (the amnion and 

 the serolemma) develop in just the same fashion. They 



