AGEICULTUEAL BOTANY, 141 



of earth mixed with paper and infected with stable manure 29 mg. of nitrogen 

 was obtained. 



The adaptation of the plant to the soil, A. D. Hall (Jour. Roy. Hort. Soc. 

 [Londo)i], 36 {1910), No. 1, pp. 1-21, figs. 11).— These papers are the third and 

 fourth lectures in a series founded in honor of Dr. Maxwell T. Masters, and in 

 them the author discusses the factors in the soil which are believed to influence 

 the distribution of plants. The questions involved are held to be fundamental 

 in plant nutrition, and some of the difficulties attending attempts to correlate 

 the composition of the soil with the plant growth are pointed out. 



Alterations in the development and forms of plants as a result of environ- 

 ment, G. Klebs (Proc. Roy. Soc. [London], Ser. B, 82 {1910), No. B 559, pp. 

 547-558). — This is a lecture delivered before the Royal Society in which the 

 author gives the results of some of his experiments upon the influence of envi- 

 ronment on plants, the effect of light, moisture, and other factors being 

 described. 



Hybridization methods in com breeding', G. H. Shull (Amcr. Breeders 

 Mag., 1 (1910), No. 2, pp. 98-101, fig. i).— The author calls attention to a de- 

 scription of a method of hybridizing corn given in Bulletin 25 of the Illinois 

 Station (E. S. R., 4, p. 904) which he says does not differ materially from the 

 methods described by B. M. East and by G. N. Collins (E. S. R., 21, p. 427). 



After discussing these various methods of corn breeding, the author describes 

 some of his experiments and summarizes his investigations, which have been 

 conducted for a number of years. He has come to the conclusion that there are 

 many distinct biotypes of corn continually mingled together in complex hybrid 

 combinations, and that there is a stimulating effect of heterozygosis. This is 

 shown, it is said, by the fact that the progeny of every self -fertilized corn plant 

 is inferior in size, vigor, and productiveness as compared with the progeny of a 

 normally cross-bred plant derived from the same source. The decrease in size 

 and vigor which accompanies self-fertilization is said to be greatest in the first 

 generation, and to become less and less in each succeeding one until a condition 

 is reached when there is probably no more loss of vigor. A cross between 

 plants belonging to two self-fertilized families results in a progeny of as great 

 vigor, size, and productiveness as are possessed by families which have never 

 been self-fertilized. 



The reciprocal crosses between two distinct self-fertilized families are equal 

 and possess the characters of the original corn with which the experiments 

 were started. The Fi from a combination of plants belonging to certain self- 

 fertilized families produces a yield superior to that of the original cross-bred 

 stock. The yield and quality of the crop produced are functions of the par- 

 ticular combination of self-fertilized parental type, and these qualities remain 

 the same whenever the cross is repeated. The Fi hybrids are no more variable 

 than the pure strains which enter into them, but the F2 show much greater 

 variation than Fi. The yield per acre of the F2 is less than that of the Fi. 



Twin hybrids (CEnothera laeta and CE. velutina) and their anatomical 

 distinctions, F. M. Andrews (Bot. Gaz., 50 (1910), No. 3, pp. 193^201).— A 

 study of twin Oilnothera hybrids, together with comparisons with (E. lamarcJc- 

 iana and dJ. biennis, was made. From this the author concludes that the twin 

 hybrids CE. Iceta and CE. velutina show themselves by their foliage and flowers, 

 and the greater density and character of the pubescence in CE. velutina, as well 

 as the form of the cells, to be distinct, and in so far as they have been investi- 

 gated, constant forms. 



The mutation theory: A criticism, G. Henslow (Jour. Roy. Hort. Soc. [Lon- 

 don], 36 (1910), No. 1, pp. IJ/Jf-lJ/S). — The author gives an account of the con- 

 ditions under which the various mutations of CEnothera lamarckiana described 



