HEREDITY AND EVOLUTION 107 



having application in the germ-cell out of which the 

 individual human life arises. So long as we are con 

 cerned exclusively with somatic life, we regard man 

 simply as a member of the animal kingdom. Our 

 data are these: the structure of the germ-cell, the 

 effects of its fertilisation, the union of two hereditary 

 principles, and thereby the start of organic movement, 

 which is the opening stage for the development of 

 individual life. To this origin we trace the entire 

 somatic results, giving all the characteristics of the 

 organic life of the species, and, in addition, carrying 

 evidence of distinctive heritage from both parents. 

 The organic movement, begun in the germ-cell, 

 completes itself in the mature embryo. Thereafter, 

 the young life, under new conditions, develops the 

 mature organism of the species. In comparative 

 biology, this completes the movement. If we go 

 further than this, we advance beyond the scientific 

 basis afforded by embryology. When we propose, in 

 the case of man, inclusion of mental powers, there is 

 need for additional evidence, which must imply either 

 additional structure, or some explanation beyond the 

 structure of the germ-plasm. Research into the re 

 lations of structure and function, has driven from the 

 field hypotheses such as Jager s postulating a soul- 

 stuff coming from decomposition of albumen in 

 various parts of the body. l To keep the present line 

 of inquiry perfectly clear, it is necessary to remark, as 

 an interpretation of the scientific position reached, 

 that it is not alleged that there is anything strikingly 

 distinctive in the structure of the human ovum, or in 

 its dependence on double hereditary principles, or in 



1 Zur Pangenesis, by Professor Dr. C. Jager. Kosmos, iv. 376, 1879. 



