MULTIPLE CHROMOSOMES 539 



nature added before it can be established that there is not main- 

 tained a specific organization. 



The belief in such an organization as this has, for bre\dty, 

 been called the theory of chromosome individuality. This has 

 perversely been much misunderstood or misrepresented. Ac- 

 cording to some the theory demands an independent existence' 

 of the chromosomes, although how this could seriously be main- 

 tained in the entire absence of any independently existing chro- 

 mosome or claim for such, it is difficult to see. In the minds of 

 others the theory demands that the chromosome shall 'make the 

 cell' — whatever that may mean. Of course no such views are 

 entertained by any cytologist and no fair interpretation of the 

 theory of chromosome indi^^duality would give occasion for 

 such statements. Because it is desired to examine the natm-e of 

 the evidence in favor of this theory, under conditions which 

 might apparently controvert it, a statement of the facts, involved 

 and an outline of the theory may be given to avoid useless dis- 

 cussion. They might take this form in the present state of our 

 knowledge (1) The cell is a complex of organs - having various 

 functions; (2) of these the nucleus, is most concerned in reproduc- 

 ing the characters of the cellular organization; (3) of nuclear 

 substances those involved in the structure of the chromatin are 

 most important in carrying out this function; (4) these substances 

 are likewise differentiated and have various roles; (5) an indica- 

 tion of this differentiation is afforded by the aggregation of these 

 substances into certain definite masses which are characterized 

 by individual peculiarities of size, form and behavior; (6) these 

 aggregates maintain their organization and reproduce them- 

 selves in each cell division; (7) their derivatives are characterized 

 by similar attributes of size, form and behavior under given con- 

 ditions; (8) such complexes therefore occur in all the cells of an 

 individual, both germ and somatic; (9) because members of a 

 species are related by descent their complexes are essentially' the 

 same; (10) the fact that a type of organization, which holds in- 

 variably for the mdividual and almost as constantly for the 

 species, prevails with slight variations through genera and even 

 a family is very strong evidence for exactness of organization: 



