334 GENETICS [Bot. Absts. 



known and higher factors must exist which regulate the mechanism of the chromosomes and 

 thereby determine sex. — Next follows a very extensive chapter on the development of new 

 biotypes. The author explains in a very logical manner and by schematic illustrations exist- 

 ing possibilities for induction of a variation in descendants, similar to a variation of the 

 parents caused by an outside impulse (modification in the embryonic state, "direct parallel- 

 induction or modification," "direct parallel-induction of mutation," "indirect parallel- 

 induction of mutation," and transmitting of a personal variation), and comes to the conclu- 

 sion that no inheritance of modifications (acquired characters) takes place. He thus rejects 

 the Lamarckian view and agrees with the opinion of the exact geneticists, but thinks it pos- 

 sible that some phenomena especially the "indirect induction of mutations," will form a con- 

 nection between the views of exact genetics and Lamarckian ideas. The experiments of Kam- 

 merer are strongly criticized. Three chapters deal with mutations, their nature and origin. 

 Author criticizes not only all superficial observation but also such esteemed investigations 

 as Tower's experiments with Leptinotarsa and the American Drosophila experiments. — This 

 section closes with an explanation of the relation between the theory of inheritance and the- 

 ories of evolution, the importance of selection, and other evolutionary questions. Author 

 points out that too little is known about mutations for discussing their relation to evolution, 

 but theoretical possibilities must be considered. — In the fourth section the author discusses 

 the importance of modern genetics for plant and animal breeding. In the last section he 

 writes about the importance of the same principles for the human race. Referring to tables 

 of pedigrees (partly carefully revised and more instructive than those in the original works) 

 the author recounts some kinds of Mendelizing qualities in man, considers polymeric cases 

 (criticizing rather severely Davenport's opinion on the mulatto-question), and discusses 

 sex-limited qualities of man. The last chapter is a well-written and moderate presentation 

 of race-hygienical questions and aims. — K. V. Ossian Dahlgren. 



2209. Waldron, L. R. Cross-fertilization in alfalfa. Jour. Amer. Soc. Agron. 2: 259- 

 266. 1919. — Two species of Medicago, saliva and falcata, were planted together in equal num- 

 bers to secure data on the amount of cross-fertilization taking place between the two species. 

 Flowering records in the Fi generation showed that the gametes of the M. saliva parent plants 

 had united with gametes from the M. falcata plants to form mature sporophytes from M. 

 sativa, to the extent of 7.48 per cent. From M. falcata 42.70 per cent of hybrid plants were 

 produced. The disparity was due probably in the main to the comparative scarcity of both 

 flowers and pollen in M. falcata. A slight, but perhaps significant, negative correlation was 

 found to exist between amount of seed produced in the parent plants and the extent of cross- 

 fertilization. — F. M. Schertz. 



2210. Warbtjrton, C. W. The occurrence of dwarfness in oats. Jour. Amer. Soc. Agron. 

 11 : 72-76. 2 fig. 1919. — In the course of studies of selections from certain oat varieties grown 

 in head rows at the Aberdeen (Idaho) substation in 1916, one row of Victory oats produced 12 

 normal plants of the variety and 8 of an entirely distinct type, these 8 being simply dense 

 tufts of basal leaves with occasional culms not over 9 inches in height, bearing very small 

 panicles. These dwarf plants for the most part failed to mature seeds before frost, though 

 watered and protected from injury. All seeds produced by both tall and dwarf plants in 

 this row were saved. — The few seeds from dwarf plants of previous year were sown in 1917, 

 and all viable ones produced dwarf plants exactly like parents. About 40 seeds from each of 

 10 of the 12 tall plants were sown in individual plant rows. Four of these 10 plants produced 

 all tall plants and 6 produced both tall and dwarf plants, in the ratio of 2.55 to 1. Some rows, 

 however, showed an exact 3 to 1 ratio. — In 1918, at Aberdeen, seed from the rows producing 

 all tall plants in 1917 again produced all tall plants in 1918, the seed from dwarf plants in seg- 

 regating rows produced dwarf plants, showing that dwarfness in this strain is recessive. — 

 All the seeds from both the tall and dwarf plants in one segregating row were sent to Dr. H. 

 H. Love at Cornell University and from another row to Prof. H. K. Hayes at the Minnesota 

 Station. The seed from the remaining 4 rows were planted by the author. — Summarizing 

 the results obtained at Ithaca, Aberdeen, and St. Paul, 65 tall plants out of 168 produced in 



