82 THE SHORTER SCIENTIFIC PAPERS 



Bateson in 1910 showed, in certain white-flowered sweet 

 peas which when crossed produce purple flowers in the 

 first hybrid generation. The results which have led to 

 the theory of coupling and of repulsion, particularly the 

 latter, where the expectancy of a pure recessive may be 

 one among many thousands, go far toward suggesting a 

 possible explanation of many so-called mutations on the 

 basis of ancestral individuals heterozygous for one or more 

 characters. 



Do the Mendelian principles assist us, however, in at- 

 taining the goal which we are seeking, namely the building 

 up of an ideal organism which will continue to transmit 

 its characters? The answer must be in the negative so far 

 as the originating of anything new is actually concerned. 

 Recessives may be obtained. Characters may be redis- 

 tributed. They were present in the forms first utilized, 

 however. 



The mutation theory formulated by De Vries in 1901 

 approximately at the time interest was being awakened by 

 the rediscovery of the hybridization principles of Mendel, 

 needs no extended explanation to those who have been 

 interested in evolution. Based on cultural experiments 

 with CEnothera lamarckiana, one of tlie evening prim- 

 roses, the appearance of relatively small numbers of forms 

 which were quite distinct from the parental species and 

 which bred true in subsequent generations, led to the in- 

 ference that evolution had in many cases proceeded by 

 discontinuous variations or mutations. 



Long series of breeding experiments followed in con- 

 nection with other organisms, both plants and animals, 

 with results quite similar to those obtained by De Vries. 

 Investigations were also made (Fischer, MacDougal, Tow- 

 er, etc.) where organisms were subjected to stimuli ab- 

 normal in their nature, with the result that a modified 

 progeny was obtained which bred true to the apparently 

 induced character in succeeding generations. Further- 

 more, cytological studies (Gates, etc.) demonstrated some 

 interesting relationships so far as differences in chromo- 

 some composition among "mutants" were concerned. 



While the evidence is far too insufficient to allow more 



