[Reprinted from THE AMERICAN NATURALIST, Vol. XLV., April, 1911.] 



THE GENOTYPES OF MAIZE 1 



DR. GEORGE HARRISON SHULL 

 STATION FOR EXPERIMENTAL EVOLUTION, COLD SPRING HARBOR, N. Y. 



THE doctrine of evolution had to overthrow the con- 

 ception of permanency of specific types, generally held 

 when Darwin 's "Origin of Species " was published, be- 

 cause that conception was then associated with the idea 

 of a separate original supernatural creation of each such 

 type. It was Darwin's great triumph that he succeeded 

 in marshaling such an array of facts pertaining to varia- 

 bility, as to convince the scientific world and through 

 the scientific world, ultimately the whole world that 

 everything is in a state of flux, and that there is no such 

 thing as permanency among living things. 



Owing to the work of De Vries and the other early 

 students of modern genetics, permanency of type again 

 demands serious scientific consideration, for such per- 

 manency is no longer incompatible with the doctrine of 

 evolution, being now associated with some form of the 

 mutation theory. The old idea of the immutability of 

 specific types was based upon almost total ignorance of 

 genetics, as was likewise the Darwinian conception of 

 fluidity and gradual change, for although many appeals 

 were made by Darwin to the experiences of plant and 

 animal breeders, it is now known that these experiences 

 were the result of no such careful control of conditions 

 or analysis of results as has been found necessary for 

 the discovery of genetic laws. The critical work of the 

 past few years has wrought a great change and the new 

 idea of permanency is gaining ground with the growth 

 of experimental knowledge. 



Without granting that we have yet reached a position 

 in which we can say definitely that types are absolutely 



1 Read before the American Society of Naturalists, December, 1910. 



