1917] AGEICULTURAL BOTANY. 523 



It is thought probable that minute biochemical differences exist which increase 

 in magnitude as the physical intimacy or relationship decreases. 



Self-pollinations and cross-pollinations in Cichorium intybus with refer- 

 ence to sterility, A. B. Sxotpr {Mem. N. Y. Bot. Oard., 6 (1916), pp. 333-^54, 

 pi. J). — The author, concluding an extensive report and discussion of pollination 

 studies dealing more particularly with C. intybus, states that a marked degree 

 of similarity in constitution between male and female gametes is the most funda- 

 mental necessity to sexual fertility. Obvious anatomical differences are deemed 

 to a large degree superficial and unessential. 



The presence of both self-fertility and cross-fertility within a nondimorphic 

 species or strain, as in C. mtybus, is considered to show that incompatibility is 

 fundamentally independent of visible difEerentiaton. The evidence on the whole 

 favors the view that for successful fertilization the element of similarity in cell 

 organization and in the physical, chemical, idioplasmic, and structural properties 

 of all the cells and tissues involved is more important than any dissimilarity that 

 can be associated with sex differentiation. 



The results in chicory also show that the development of self -incompatibility is 

 not closely correlated with conditions in the immediate parentage. In physio- 

 logical incompatibilites that appear in the selfing and crossing in such nondimor- 

 phic species as C. intybus and Cardamine pratensis, also in such dimorphic spe- 

 cies as Primula sinensis, it appears that the grade of sex differentiation within 

 the individual may involve sufficient relative dissimilarity to limit or prevent 

 pollination. 



Studies on the blooming of hemp, G. Havas (Kis^rlet. Kozlem., 18 {1915), 

 No. 5-6, pp. 908-919, pis. 2, figs 5). — The modes of succession in the appear- 

 ance of blooms at different levels of both male and female plants of Cannabis 

 sativa are described. It is stated that blooming and pollen dispersal by the 

 male flowers (the period between which occupies about seven hours) occur 

 mainly during the night and morning, a minimum rate prevailing in the lat- 

 ter part of the night and the forenoon. 



The persistence of the style on fruits, C. Campbell {Atti R. Accad. Lincei, 

 Rend. CI. Sei. Fis., Mat. e Nat., 5. ser., 25 {1916), I, No. S, pp. 178-183, figs. 2).— 

 Cases are described, chiefly in lemons, in which the persistence and develop- 

 ment of the style after fertilization resulted in a deformed fruit. It is 

 thought that in case of relatively rapid development just after pollination the 

 formation of a fission layer proceeds normally, while in case of slower de- 

 velopment this does not occur and the persistent style develops as part of 

 the fruit. 



The determinative action of environic factors upon Neobeckia aquatica, 

 D. T. MacDougal {FLwa [Jenal, n. ser., 6 (1914), No. S, pp. 264-280, figs. U).— 

 Experimentation through which 2V. aquatica has been carried, including the 

 keeping of cultures as terrestials or aquatics in environments and under 

 conditions differing very widely, has shown that this plant, which endures 

 an extremely wide range of conditions, is capable of considerable modifica- 

 tions in several directions by alternations of environment. The changes 

 appear not to be adaptive in many cases, though determined by environment 

 to a much greater degree than in case of Proserpinaca, Slum, or probably 

 any other so-called polymorphic species, yet the reaction to such external 

 agencies is not considered to be a direct or physical adjustment. 



Plant ecology and the new soil fertility, C. B. Lipman {Mem. N. Y. Bot. 

 Gard., 6 {1916), pp. 319-321). — This is a brief discussion of the benefit con- 

 sidered to be derivable from closer cooperation between plant ecologists and 

 soil scientists regarding such factors as the composition and concentration of 



