428 EXPERIMENT STATION RECORD. 



may be made with a higli degree of accuracy beyond tbe point where Molisch 

 regarded the stomata as practically closed. Also, these more sensitive indicators 

 are less injurious to the cells than are benzol and xylol. 



Heterozygosis in evolution and in plant breeding, E. M. East and H. K. 

 Hayes (Z7. S. Dept. Agr., Bur. Plant Indus. Bui. 2Jt3, pp. 58, ph. 8).— In co- 

 operative work between this Department, the Connecticut State Station, and 

 the Bussey Institution, the authors have studied heterozygosis in evolution and 

 in plant breeding, predicating their belief that INIendel's law — that is, the 

 segregation of character factors in the germ cells of hybrids and their chance 

 recombination in sexual fusions — is a general law; that stimulus to develop-' 

 ment is greater when certain, or possibly all, characters are in the heterozygous 

 condition than when they are in a homozygous condition ; and that this stimulus 

 to development is cumulative up to a limiting point and varies directly with 

 the number of heterozygous factors in the organism. 



Their studies were made with 30 varieties of maize and several species of 

 Nicotiana. As a result of their investigations the authors believe they have 

 demonstrated that " the decrease in vigor due to inbreeding naturally cross- 

 fertilized species and the increase in vigor due to crossing naturally self- 

 fertilized species are manifestations of one phenomenon, heterozygosis. Cross- 

 ing produces heterozygosis in all characters by which the parent plants differ. 

 Inbreeding tends to produce homozygosis automatically. The phenomenon 

 exists and is in fact widespread in the vegetable kingdom. Inbreeding is not 

 injurious in itself, but weak types kept in existence in a cross-fertilized species 

 through heterozygosis may be isolated by its means. Weak types appear in 

 self-fertilized siiecies, but are eliminated because they must stand or fall by 

 their own merits." 



The experimental data upon which these conclusions are based have been 

 obtained entirely from plants, but observations on animal hybrids and pub- 

 lished records lead the authors to believe that the facts are the same among 

 animals, and that their conclusions will apply equally to the animal and the 

 vegetable kingdoms where organisms are reproduced sexuaUy. 



A bibliography is appended. 



The inheritance of red color, and the regularity of self-fertilization in 

 the common jute plant, R. S. Finlow and I. H. Burkill (Mem. Dept. Agr. 

 India, Bot. Ser., Jf {1912), No. Jf, pp. 73-92).— From 1902 to 1907 the authors 

 made a survey of the different races of jute cultivated in India, and as a 

 result of their survey they recognize 33 races, including 3 which are grown as 

 vegetables. These are grouped according to color tyi^es, and the inheritance 

 of color in them is shown. 



It is stated that when a pure green jute is crossed with a fixed red plant the 

 Mendelian law is obeyed, the red acting as a simple dominant. The Fi genera- 

 tion of hybrids appears to consist of plants of one tint of redness. The F; 

 generation, on the other hand, varies widely in the amount of red color the 

 plants contain. 



The authors in their studies found that self-fertilization is the rule with 

 this plant, probably not more than 2 per cent of the plants under the most 

 favorable conditions being the result of cross breeding. 



Department of botanical research, D. T. MacDougal ( Carnegie Inst. Wash- 

 ington Year Book, 10 (1911), pp. 49-68, pi. 1). — ^An outline is given of the inves- 

 tigations carried on by the staff attached to the botanical research laboratory 

 at Tucson, Ariz., a number of the investigations having been previously reported 

 upon at length (E. S. R., 25, pp. 219, 327, 732; 26, pp. 433, 532, 628; 27, pp. 

 29, 329, 331). 



