522 EXPERIMENT STATION BECORD. [Vol. 43 



In all self-compatible species investigated, except Raphanns 8ativu.i and 

 Linum gmndiflorum, self-incompatibility and self-compatibility are highly vari- 

 able. The variations are mostly indiscriminate, though there are cases of 

 marked correlation with conditions as regards age or vegetative vigor during 

 the period of bloom. In some cases at least embryo abortion appears to 

 be due to physiological incompatibility. Repeated selection does not elimi- 

 nate the extreme fluctuations, though tending toward the establishment and 

 maintenance of highly self-fertile races. Continued self-fertilization in chicory 

 has not decreased self-compatibility or vegetative vigor. It is stated that all 

 results favor the view that incompatibilities arise primarily in the ontogenetic 

 processes of physiological differentiation of sex organs, and are not determined 

 by either individual stuffs or line stuffs of deflnite hereditary value. As far as 

 general constitution is concerned, similarity in parents favors fertility. Appar- 

 ently, successful fertilization depends fundamentally on similarity. 



Probable bearings of data and conclusions reported by investigators are 

 indicated, and new data as obtained witii different plants are presented in 

 detail with interpretations. 



Both self-fertility and cross-fertility within a species are considered original 

 and primitive conditions as compared with self-incompatibility and cross-in- 

 compatability. Self-fertility is more primitive than cross-fertility. In her- 

 maphrodites incompatibilities have arisen and are arising in species through 

 fluctuating variation in the physiologcal differentiation of the sex organs. The 

 evidence supporting the general conclusion in this paragraph is outlined with 

 interpretative discussion. 



Sexuality is regarded as a cyclic recurring condition which makes possible 

 the fusion of cells and nuclei and the pairing of chromosomes. The incompati- 

 bilities exhibited in processes of fertilization are due to physiological proper- 

 ties that are acquired during sex differentiation. The behavior of both self- and 

 cross-incompatibilities affords no proof that unlilceness in sex organs favors 

 tJie union of gametes or that some element of similarity leads to incompatibility. 



A study of Allocarya, C. V. Piper {U. 8. Natl. Mus., Contrib. U. S. Nat. 

 Herbarium, 22 (1920), pt. 2, pp. VII-j-79-113). — Results are given of a study 

 of Allocarya, a genus of boraginaceous plants, chiefly of the western United 

 States. 



Revisions of North American grasses, A. S. Hitchcock and A. Chase 

 {U. S. Natl, iliis., Contrib. U. S. Nat. Herharium, 22 (1920), pt. 1, pp. X+77, 

 p?s. 24, figs. 20). — The authors describe species recognized under the genera 

 Ichnanthus, Lasiacis, Brachiaria, and Cenchrus. 



The diecious nature of buffalo grass, J. H. Schaffner (Bill. Torrey Bot. 

 Club, 47 (1920), No. 3, pp. 119-124).— A study in 1919 at Morganville, Kans., 

 of buffalo grass (Bulbilis (lactyloicles) gave no support to the view expressed by 

 certain investigators that a monecious form exists, though certain possibilities 

 are indicated. 



It is stated that this grass is holding its own very well under civilized condi- 

 tions, and toward its eastern limit is spreading in pastures and abandoned 

 fields, because its strongest competitors (Andropogon scoparius and A, furcatus) 

 are nmch more subject to destruction througli grazing and trampling of live 

 stock. 



Composition and density of the native vegetation in the vicinity of the 

 Nortliern Great Plains Field Station, J. T. Sarvis (.Jour. Agr, fiesearch 

 [17. S.], 19 (1920), No. 2, pp. 63-72, pis. 3, figs. 2).— In a contribution f^-om.the 

 Bureau of Plant Industry, U. S. Department of Agriculture, the author reports 

 on cooperative experiments with the North Dakota Experiment Station, ^on^ 



