320 PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 



such waste of capital and energy. Such studies must include the 

 hypogean portions of plants as well as the aerial portions, and 

 the recent studies of root ecology and root physiology are sug- 

 gestive of the large importance of such investigations. 



BREEDING 



All plants cultivated for any considerable length of time 

 are very dififerent from their wild or their imported progenitors. 

 Most of these results of breeding have been accomplished by 

 empirical practice. Only within the last two decades have such 

 methods given way largely to scientific procedure, based mainly 

 on evolution and heredity. 



Artificial hybridization has produced many cultivated plants 

 of great value. By this method, we are breeding larger and more 

 hardy plants, improving the food qualities of plants or plant 

 parts, obtaining plants adapted to certain climates or resistant to 

 disease, and securing desirable tastes and odors. The marked 

 vigor of certain hybrids is now known to be but an extension of 

 the well-known fact that cross-fertilization results in stronger 

 individuals. In hybridizing, we pass beyond the species limit and 

 secure increase in variation and often in strength as well. Recent 

 work on corn, by which stronger plants and better yield are 

 secm^ed by intricate hybridizing is an illustration of the possi- 

 bilities. 



The rediscovery of Mendel's laws a decade and a half ago 

 has given an explanation of the results of hybridizing, has in- 

 fluenced biological thought profoundly, and has resulted in the 

 accumulation of a large amount of unassimilated data. It had 

 been known previously that succeeding generations of hybrids 

 are more stable and often more desirable than first generations, 

 and Mendelism has given the clue to cause. Mendel's view of 

 unit characters in gametes remains much as he promulgated it, 

 but other Mendelian concei)tions have been modified consider- 

 ably in the fifteen years intervening since rediscovery. Breeders 

 admit the validity of Mendelism in a general way, but dominance 

 and recession do not seem to follow Mendel's fixed laws closely 



