Hutchison: Heritable Characters of Maize 



83 



is now available for making this three 

 point test. 



Shrunken has also been crossed with 

 another aleurone factor / i, the exist- 

 ence of which was first established by 

 East and Hayes (1911). The inter- 

 action of the recessive allelomorph i of 

 this factor pair with the dominant 

 allelomorphs of three other factor pairs 

 A a, C c and R r is necessary for the 

 development of aleurone color (Emer- 

 son, 1918). When the dominant allelo- 

 morph / is present no color develops. 

 A homozygous red aleurone shrunken 

 plant with the constitution i i sh sh was 

 crossed with a homozygous non- 

 shrunken plant which was also homo- 

 zygous for / and, therefore, had 

 colorless aleurone. Its genetic consti- 

 tution for the factors in question was 

 I I Sh Sh. The immediate kernels 

 produced were colorless and non- 

 shrunken. Several Fi plants produced 

 by these kernels were backcrossed to 

 the double recessive. Twenty-eight 

 backcrossed ears were obtained with a 

 total of 7,294 kernels. All four combi- 

 nations of the characters in question 



appeared among these kernels, the 

 numbers in each class being as follows : 



The parental combinations here total 

 7,034 while the other two total only 

 260. It is evident, therefore, that the 

 factor pair / i also belongs with the 

 C c Sh sh Wx wx linkage group. The 

 crossover percentage for / i and Sh sh 

 in this case is 3.6. One of these back- 

 crossed ears is shown on the right in 

 Figure 22. 



The very close approximation of 

 the Sh sh — C c linkage relation by that 

 of Sh sh — / i suggests three interesting 

 possibilities. C c and / i are (1) very 

 closely linked, (2) they are on opposite 

 sides of Sh sh and approximately 

 equally distant, or (3) they are allelo- 

 morphic. It is impossible at present 

 to determine which of these possibilities 

 is correct but investigations are now in 

 progress which are expected to throw 

 some light upon the problem. 



Literature Cited 

 Bregger, T. Linkage in maize: the C aleurone factor and waxy endosperm. Amer. Nat. 52: 57-61- 



1918. 

 Collins, G. N. and Kempton, J. H. Inheritance of waxy endosperm in hybrids of Chinese maize. 



International Conference of Genetics, Paris, 4: 547-556. 1911. 

 East, E. M. and Hayes, H. K. Inheritance in maize. Connecticut Agr. Exp. Sta. Bui. 167: 1-142. 



1911. 

 Emerson, R. A. A fifth pair of factors, A a, for aleurone color in maize, and its relation to the C c and 



R r pairs. CorneU Univ. Agr. Exp. Sta. Mem. 16: 227-289. 1918. 



Fellowship in Crop Breeding 



There will be a fellowship in the 

 study of crop improvement at the 

 Michigan Experiment Station, East 

 Lansing, Michigan, to be filled on or 

 before September 1st, 1921. It is a 

 half-time fellowship, open to graduates 

 of our Universities with farm experience 

 or graduates of Agricultural Colleges, 

 who have had a good course in genetics, 

 the more genetics the better. 



The holder of the fellowship is ex- 

 pected to complete a master's, degree 

 in two years, majoring in plant breed- 

 ing and taking his minor in some other 

 department. Half of his time will be 

 devoted to actual crop improvement 



work, connected with the Department 

 of Farm Crops. 



The breeding work during the coming 

 year will include work on corn, oats, 

 rye, wheat, beans, alfalfa, clover, fiber, 

 flax, hemp, potatoes, sugar beets, 

 timothy, and winter vetch. 



The candidate would need to furnish 

 a copy of his grades from the Regis- 

 trar's records, and give references to 

 those who know of his abilities. The 

 fellowship offers S800 for half time 

 during each of two years. Interested 

 persons should communicate with the 

 Department of Farm Crops, Michigan 

 Agricultural College, East Lansing, 

 Michigan. 



