84 The Unity of the Organism 



ential, that is, that it pertains to a particular species or 

 kind of organism, it would put an end to the notion by 

 which recent genetic science has been so largely dominated, 

 that the problem of how the series came to be thus specific 

 or differential may be solved by speculation, and it would 

 incite geneticists to efforts to solve the problem by obser- 

 vation aided by experiment. It is impossible to refute the 

 charge that genetics is to-day more interested in an elab- 

 orate system of conceptions of speculation, in other words 

 than it is in observed or possibly observable phenomena. 

 We cannot keep too constantly before our minds the fact 

 of our almost complete ignorance of how any substance 

 becomes hereditary substance whether through the "inheri- 

 tance of acquired characters" or in any other way. Hence 

 mere speculation on the subject after the manner of the pan- 

 gens idea is much worse than nothing if permitted to run into 

 a bewildering and enslaving system like that of the germ- 

 plasm theory as it came from Weismann's mind. Neverthe- 

 less it is quite germane to the present discussion to point 

 out that whatever might be the nature of the chemical ac- 

 tion, whether enzymic or some other, through which the 

 series of ontogenic transformations should be accomplished, 

 the character and subtlety of these processes seem to make 

 them, more than any others we know, competent with some 

 modification to serve as the go-between for impressing the 

 germinal material with the latent attributes of the species. 



Inconclusiveness of the Cytological Evidence Usually Ap- 

 pealed to in Support of the Chromosome TJieory 



And this leads to the concluding statements of this dis- 

 cussion. The three categories of cytological fact which 

 have been weightiest in the formation and maintenance of 

 the chromosome theory of heredity are the individuality and 

 continuity, chiefly numerical, of the chromosomes from par- 



