126 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE 



paper by Hays (1912) dealing with correlation and inher- 

 itance in tobacco. Here calculating the constants for two 

 parental types combined (401 and 403) in respect to num- 

 ber of leaves and height of plant it is found that the Coeffi- 

 cient of Variation has decidedly decreased through the 

 hybridization, although the number of combinations 

 (amphimutations) have increased. 



There exists the possibility, however, that variability 

 will appear to be increased when forms having the same 

 phenotj^pe but different genotypes are bred together. Such 

 a condition may be illustrated by the two white strains of 

 sweet peas crossed by Bateson which produced purple flow- 

 ers in the first (F,) hybrid generation, and purple, pink, 

 mixed, and white flowers in the second (F.) hybrid genera- 

 tion. New combinations occur, but there is evidence of no 

 increase in unit characters nor is there any actual increase 

 in the variabilit}' with which we are concerned. 



Turning for a moment to size characters the influ- 

 ence of cross breeding or conjugation is of decided interest 

 inasmuch as facts bearing on the solution of the problem as 

 to how size may be increased to the physiological limit, even 

 though the results hold for a single generation, have the 

 greatest practical value for the future of agriculture and 

 animal breeding. 



It should first be noted that size in a unicellular organ- 

 ism is dependent on the absolute size of the individual cell 

 with a limit undoubtedly imposed by laws governing the 

 ratio between volume and surface in connection with 

 osmosis. In multicellular organisms, however, size char- 

 acters may depend either upon the size or the number of 

 the component cells or upon both factors. This distinction 

 possibly explains an apparent diversity in results obtained 

 in the two groups. 



Darwin, Mendel, and others who have seriously con- 

 sidered the question have recognized that hybrids among 



