Variation and Heredity 491 



1. A study of the methods and manipulation of crossing, con- 

 sulting such references as 



BAILEY, L. H. Plant Breeding. Pp. 344-358. 

 OLIVER. Bureau of Plant Industry. Bui. 167 : 39 pp. 



FIG. 141. Dahlia flowers after depollination by means of a stream of 

 water. [Photograph from Bureau Plant Industry.] 



2. The results of crossing. In the latter case parents, to- 

 gether with first and second generation crosses, should be com- 

 pared with respect to characters, following the suggestions in 

 sections 294-297. Fresh material is most desirable, but if it 

 may not be had at the time desired, alcoholic or dried material 

 will serve adequately for the study of many characters. 



REFERENCES 



BAILEY, L. H. Plant Breeding. 4th Ed. 463 pp., 20 figs., 1907. 

 BATESON, W. The Progress of Genetics since the Rediscovery 



