On the Mechanical Conception of Nature. 689 



the organism to the influences of the environ- 

 ment. 



It will be immediately perceived how exactly 

 the processes of phyletic and of ontogenetic de- 

 velopment coincide, not merely in their external 

 phenomena but in their nature, if we trace the 

 consequences of the existing knowledge of the 

 structure of the animal body. Although we may 

 not entirely agree with Haeckel's doctrine of indi- 

 viduality in its details, its correctness must on 

 the whole be conceded, since it cannot be dis- 

 puted that the notion of individuality is a relative 

 one, and that several categories of morphological 

 individuals exist, which appear not only singly as 

 physiological individuals, i. e. as independent living 

 beings of lowest grade, but which can also 

 combine to form beings of a higher order. 



But if we admit this, we should see with Haeckel 

 nothing but reproduction in the origination of a 

 high organism from a single cell, the egg; this 

 reproduction being at the same time combined 

 with various differentiations of the offspring, i.e. 

 with adaptations of the latter to various con- 

 ditions of life. Not even in the fact that the 

 tissues and organs of a single physiological in- 

 dividual stand in great dependence upon one 

 another through physical causes," is there any 



17 [In a recently published work by Dr. Wilhelm Roux this 

 author has attempted to work out the idea of an analogy 



