320 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 



The flowers on one of the derivatives, as they may be called, were so 

 completely lacking in color as to be a cream-white, this derivative' 

 being designated as albida, while the other showed some marginal 



color and a rusty tinge and was designated as rufida Seeds of 



the original two derivatives were -sowed in the greenhouse. But one 

 plant of albida, the most extreme departure, survived, while four of 

 rufida were secured." MacDougal compared these second generation 

 seedlings with seedlings from the original stock of the species, noting 

 differences in size and margin of leaves, length of petioles and number 

 of marginal glands. He found that the differences shown by the first 

 generation appeared again in the second generation. Striking as these 

 results appear it must be admitted that it would be difficult, on account 

 of the small numbers of individuals differing from the parent type, to 

 prove "satisfactorily to the biometrician that they were not mutations 

 which would have occurred regardless of the ovarial treatment. 



What appear to be germinal variations in the tomato have been 

 induced by intensive feeding. T. H. White tested the effect of dried 

 blood, dissolved phosphate rock, sulphate of potash and iron filings 

 all in excessive amounts, and (with the exception of the iron) in 

 various combinations, on the Red Cherry tomato. The lack of data 

 on control cultures of seedlings from the same parent as the experi- 

 mental cultures makes it impossible to compare the actual amount 

 of permanent variation produced. T. H. White states that measure- 

 ments "show that the plants of the sixth generation grown under the 

 influence of the dried blood are one-third larger in height, length of 

 leaf and size of fruit, than those of the second." The author con- 

 cludes that "there can be no doubt .... that, in the case of Red 

 Cherry treated with dried blood, there is permanent variation to the 

 third generation." If these results are corroborated by more care- 

 fully planned and rigidly controlled experiments they will add the 

 weight of scientific proof of a principle in plant breeding long since 

 recognized on empirical grounds, to wit, that the introduction of wild 

 plants into intensive cultivation induces variation. Furthermore, it 

 suggests a possible means for rapid permanent improvement of wild 

 forms with which hybridization may be impracticable. 



In experiments on lower animals, e.g., the protozoa, the same 

 difficulty is met with as has been encountered in bacteria and yeasts, 

 hi that it is manifestly impossible to distinguish between somatic and 

 germinal variations. Moreover, in most of these experiments, as with 

 most of those on higher animals, the necessary conditions for rigid 



