COXCLUSIOXS. 39 



The embiyo that forms as a result of a cross-pollmation is, of 

 course, hybrid in nature and may differ from the female parent. 

 Owing to a peculiar double fertilization that obtauis m corn the 

 developing endosperm as well as the embryo is contributed to by 

 the pollen and may resemble the male parent. With respect to the 

 characters of the endosperm we are already dealing with the first 

 generation of a hybrid and the general law of uniformity in the fii-st 

 generation seems to hold in most instances. There may be no pre- 

 dicting what the nature of the grain will be, but those plants resulting 

 from the same cross may usually be depended upon to be alike. 



The diversity that appeare in the seed color of fu"st-generation 

 hybrids is only an apparent exception to the general iiile of uniform- 

 ity in first-generation hybrids. The endosperm in which this diver- 

 sity appeal's is in reality the second generation of the hybrid and 

 may consequently show the diversity characteristic of second-genera- 

 tion hybrids. 



CONCLUSIONS. 



The com plant is naturally cross-fertilized and requires the stimulus 

 of crossing to produce maximum yields. Methods of close breeding 

 that can be applied to other crops with advantage do violence to 

 the nature of the plant and tend to reduce the vigor of growth and 

 the yield of grain. 



As a result of the peculiar habits of reproduction of the corn plant, 

 the raising of hybrid seed does not require any special skill or any 

 large increase of labor. The cost involved is insignificant in com- 

 parison with the increased yields that are obtamed. 



Xo reason is apparent why the vigor of hybrids may not be regularly 

 utilized to increase the yields of the corn crop. A refusal to take 

 this factor mto account would be like rejectmg the use of commercial 

 fertilizers or failing to take advantage of the increase that may be 

 obtained by selective breedmg. 



The plantmg of fu-st-generation hybrid seed as a method of secur- 

 ing a larger crop is to be considered as entirely distinct from the idea 

 that superior varieties can be bred by hybridizmg or crossing. Crosses 

 between distinct varieties or strains at once increase the yield, but to 

 maintain this high performance the cross must be made anew each year. 



Experiments to determme the value of fii-st-generation hybrids 

 have been made at various times since 1878, but in an isolated and 

 disconnected manner and usually without any adec[uate apprecia- 

 tion of the possibilities of this method as a regidar element of farm 

 practice. 



In the literature which has thus far been examined, 19 crosses have 

 been reported. With a single exception these hybrids gave larger 



191 



