214 



Plant Genetics 



Presence and absence hypothesis, 



40 

 Protoplasmic connections, 18 

 Protozoa, inheritance in, 113 

 Pteridophytes, sex determination 



in, 190 

 Pure-breeding hybrids, 47, 76 

 Purity of gametes, 31 



Quantitative characters, inherit- 

 ance of, 63, 7Q 



Reciprocal crosses, 29 

 Reinfection and inheritance, 25, 



100 

 Responses, 70 

 Reversion, S4, 83 

 Riccia, sex in, 189 

 Riddle, Oscar, 181, 194, 202 

 Running out, 159 



Saprolegnia, parthenogenesis in, 



"S 

 Segregation, 31; essential feature 



of, 125; somatic, 100 

 Selaginella, sex in, 190 

 Selection, effect of, 80, 106 

 Selectionists, work of, 114 

 Self-sterility, 133; and apogamy, 



120 

 Semi-sterility, 138 

 Sex chromosomes, 178 

 Sex determination, 117 

 Sex: discovery of, in plants, 4; 



significance of, 10, 134 

 ShuU, G. H., 40, 159, 173, 196 

 Sibs, 160 

 Simplex, 42 

 Single dose, 34 

 Somatic segregation, loi 

 Sphaerocarpus, sex determination 



in, 184, 187 

 Spirogyra, inheritance in, 131 

 Spores, inheritance by, 121 



Staleness of pollen and sex, 208 

 Sterile pollen in crypthybrids, 48 

 Strasburger, E., 184, 187, 193 

 Supplementary factors, 57, 60, 78, 



128 

 Sykes, M. G., 184 



Taraxacum, parthenogenesis in, 

 116 



Tetraploidy in mosses and Oeno- 

 thera, 200 



Thalictrum: parthenogenesis in, 

 116; sex in, 195 



Tobacco: hybrid vigor in, 166; 

 self-sterility in, 143 



Transportation hypothesis, 5, 68 



Trihybrid ratio, 39 



Triple fusion, 146, 149 



True-breeding hybrids, 76 



Unit characters, 29; modification 



of, 104 

 United States Committee on 



Breeding Nut and Forest Trees, 



report of, 21 

 Use and disuse, effect of, 25 



Vegetative apogamy, 115; and 



true-breeding hybrids, 48 

 Vigor, hybrid, 158 



Walter, H. E., v, 19 



Water molds, parthenogenesis in, 



"S 

 Webber, H. J., 151 

 Weismann, August, 6, 13, 17, 25, 



68, 113, 134 

 White, Orland E., 96 

 Wiedersheim, W., 19 

 Wilson, E. B., 203 



X-chromosomes, 178 

 Xenia, 148; abnormal, 151 



Yamanouchi, Shig^o, 116 



Zederbauer, E., 20 



