No. 531] THE GENOTYPE HYPOTHESIS 157 



tion as the normal case. If we accept the suggestion of 

 antocatalysis as an essential factor for the propagation of 

 living matter in general, and hence eo ipso, for the growth 

 or multiplication of genotypical constituents, we might in 

 case of impure segregation expect frequently to find 

 " dominants" in the progeny of "recessives" ; and the 

 numerical proportions of the dominants and recessives in 

 consecutive generations must be rather irregular. But 

 this is not the case. The recent experiments of Darbi- 

 shire quoted above demonstrate in a beautiful manner the 

 purity of segregation during subsequent generations in 

 Mendel's classical object, the pea. 



Francis Bacon says: "Human understanding easily 

 supposes a greater degree of order and equality in things 

 than it really finds. " So we may in modern genetics be 

 aware of the relativity and narrowness of our provisorial 

 explanations, remembering Bacon's warning that "many 

 things in nature may be sui generis and irregular!" 

 Among the irregularities in heredity we may reckon the 

 mutations, observed in nature as well as in more precisely 

 defined conditions of artificial experiments. From the 

 famous observations of De Vries and the indications of 

 several earlier authors, to the modern experimental 

 researches of MacDougal, Standfuss, Tower. Blaringliem 

 and others, all evidences as to mutations point out the 

 discontinuity of the changes in question. Here we need 

 not enter the question ; it is sufficient to state that the es- 

 sential point is the alteration, loss or gain of constituents 

 of the genotype. The splendid experiments of Tower as to 

 Leptinotarsa have in the most evident manner shown that 

 the factors which produce the mutations in this case, viz., 

 the temperature and state of moisture, are able to act in 

 a direct manner upon the genotypical constitution of the 

 gametes ; and Tower has noted the occurrence of Mendel- 

 ian segregation in hybridizing his mutants with the 

 original unaltered biotypes. There may in some cases 

 be certain puzzling irregularities to be explained by 

 future researches, but it is evident that in all such muta- 



