A DYNAMICAL HYPOTHESIS OF INHERITANCE. 33 



times and places in the course of development. We thus 

 escape, too, the mistake of assuming that a part of a germ 

 controls the whole, a proposition that has been so long advo- 

 cated by one school of biologists that it is astounding that its 

 fallacy has not long since been more generally understood. 

 Such a doctrine is not credible in the face of the fact that we 

 know of no development except that which takes place in inti- 

 mate association with cytoplasm, which seems to be the prin- 

 cipal theater of metabolism and growth. We cannot conceive 

 of the transformations of a germ without considering the 

 metabolism of all its parts, such as nucleus, cytoplasm, cen- 

 trosomes, archoplasm, chromatin, spindles, astral figures, mi- 

 crosomata, etc. " Tendencies " and "proclivities" are words 

 that have no legitimate place in the discussion of the data of 

 biology any more than they have in natural philosophy or 

 physics. Karyokinesis, now admittedly inseparable in thought 

 from the idea of multicellular development, is a rhythmical 

 process so complex in its dynamical aspects as to some extent 

 lead one unwittingly to underestimate the absolute continuity 

 of the accompanying processes of metabolism. But that is no 

 reason why the importance of nuclear metamorphosis should 

 be exaggerated at the expense of the far more important forces 

 developed by metabolism and growth. In fact the "ids," 

 " idants," etc., of that school of biologists are not causes but 

 mere effects, produced as passing shadows, so to speak, in the 

 operation of the perfectly continuous processes of metabolism 

 incident to development. Reciprocal relations are sustained 

 between nucleus and cytoplasm of such importance that the 

 transformation or fission of the one is impossible without the 

 other. 



The so-called " reducing divisions" probably have nothing 

 but a passing and purely adaptive physiological significance in 

 every ontogeny of ova and sperms. The far-fetched and extraor- 

 dinary teleological significance given by some to the reducing 

 divisions, would lead one to suppose that the clairvoyant wis- 

 dom of the original egg that thus first threw out the excess of 

 its ancestral " germ-plasm " in order to save its posterity from 

 harm through the fatality of reversion thus entailed, was 



