m'clung: cytology and taxonomy. 205 



the somatic characters, and how explain their differences in 

 the formation of body-cells and germ-cells from the same fer- 

 tilized egg? Here we have the problem of heredity stated in 

 cytological terms, and any theory offered in explanation must 

 conform itself to the known facts. I am of the opinion that in 

 our work upon the classification of organisms we have been 

 much inclined to regard only the end stage of the process of 

 development. A starfish has not been for us a starfish until it 

 has acquired its radial symmetry and its adult organs. I be- 

 lieve that in this we are mistaken. The egg of the starfish per- 

 forms its functions in just as specific a manner, and differs 

 from the egg of a sea-urchin as truly, as do .these same organ- 

 isms differ after a few weeks of development. We must realize 

 that an organism functions from its very beginning and that 

 it does this differently from any other individual. We may not 

 now be able to perceive these differences of individuals in the 

 one-celled condition so clearly as we do when they are many- 

 celled, but this is due to our lack of knowledge and not to the 

 absence of variation. That one cell is sufficient for the identi- 

 fication of the species is clear enough from my study of Hes- 

 perotettix and other Orthoptera. 



We must indeed recognize that organisms are specifically 

 different throughout their ontogeny, and that they exhibit the 

 functions of protoplasm specifically in every case — not one 

 function, but all of them. It would accordingly be as difficult 

 to add sex to an animal at some late stage of development as it 

 would be for the egg starfish to change into an adult sea-urchin. 

 The organization is inherent in the individual from the begin- 

 ning; its method of expression differs, however, from stage to 

 stage. Therefore we must conclude that the parts of the whole 

 also differ progressively. Perception, movement, metabolism 

 and reproduction are functions of the one cell just as truly as 

 they are of the multitude of cells that results from its division. 



If chromosomes are centers of influence governing alwaj^'s 

 the manifestation of specific energies, then they must at every 

 stage of development, both ontogenetic and phylogenetic, ex- 

 hibit the same properties. In so doing they show themselves 

 subject to the same laws of change that obtain in the differen- 

 tiation of cells, for the nature and extent of their influence 

 vary progressively. I think it is reasonable to conclude thus, 

 for, if our assumption regarding the sex-determining nature 

 of the accessory chromosome be correct, this is just what we 



