A CRITICAL EXAMINATION 31 



a dozen other hypotheses which would "fit" 

 these aberrant ratios equally well. Furthermore, 

 if he were also a biologist he could no doubt give 

 each hypothesis a cytological flavor, and bring 

 forward observations upon the chromosomes or 

 other cell constituents in its support. 



It is important in this same connection to con- 

 sider carefully the results of Morgan regarding 

 linkage phenomena. He and his students 1 have 

 collected a great body of data regarding "linked" 

 inheritance in Drosophila, which they interpret 

 on an hypothesis which locates the causal de- 

 termining factors for particular characters not 

 merely in particular chromosomes, but further in 

 particular places in the chromosomes. The in- 

 genuity and keenness of insight displayed in the 

 experimental analysis by which these results have 

 been obtained must compel the unreserved ad- 

 miration of any one who carefully examines them. 

 This Drosophila work will stand as a masterpiece 

 of experimental research. Logically considered 

 the evidence in favor of the chromosomal hypothe- 

 sis adopted by Morgan is based primarily on the 

 general fact that the chromosomes, if they be 

 assumed to behave in certain postulated ways, 

 would furnish a mechanism which would account 

 for the observed breeding results. The primary 



1 In a series of papers appearing during the last few years in the 

 Jour, of Expt. Zool., Science, Amer. Nat., Zeitsch. ind. Abst.- 

 Vererb. Lehre, etc. 



