ORTHOGENESIS 341 



differentiation generally, and how delicate the balance 

 required between a due pair of opposites in Nature. Without 

 the fundamental necessity of adaptation according to cosmic 

 (bio-economic) needs, i.e., without symbiogenesis, the high 

 duties required by reciprocal differentiation could not be 

 discharged, nor could orthogenesis unaided by symbiogenesis 

 keep the organism for long on the path of progressive reciprocal 

 differentiation. We have in the extreme sexual dimorphism 

 of parasites also a kind of orthogenesis, although in the 

 absence of symbiogenesis it is, as I have shown, unbalanced and 

 pathogenetic in character, and it is difficult to suppose that in 

 such cases sperm-nucleus and egg-nucleus are really perfect 

 complements of one another. Frequently the sperm appears as 

 nothing more than the merest spark to set the germ going and 

 moving along further down the inclined plane of pathogenesis, 

 towards extinction; i.e., the movement is definite in direction 

 but retrogressive. 



The correlative alteration of the sexual products leads to the con- 

 sideration of a fact which seems to me to cry loudly against Weissmann's 

 assumption that those products remain essentially unaffected by the 

 condition of the body from time to time. I refer to the great correlative 

 influence which conversely the condition of the sexual products, namely 

 their maturity (puberty) and their artificial removal (castration) as well 

 as the extinction of their powers in old age, has upon the condition of 

 the whole body. This relation is so well known that it is unnecessary 

 for me here to give any proof of it. But it is at the same time one 

 of the most striking examples of correlation, and certainly affords most 

 valuable support to my conclusion that changes in the characters of the 

 body appearing suddenly through correlative growth may lead to the 

 formation of new species without the assistance of selection. 



We have seen that correlation as a part of symbiogenesis 

 is a great factor in evolution, whilst there is a vast amount of 

 correlation associated with pathological factors making for 

 pathogenesis and ultimate extinction. Prof. Eimer thinks that 

 through correlation new species can arise without the aid of 

 selection : 



As soon as something or other in the original state, in the original 

 arrangement of the parts of the organism, is changed, other parts also 

 are set in motion, all arranges itself into a new whole, becomes or 



