130 EXPERIMENT STATION EECOED. 



to be wholly one of rate of growth. In the selfed pistils the pollen tubes devel- 

 oped steadily at a rate of about 3 mm. in 24 hours. Since the maximum life 

 of the flower was found to be about 11 days, the tubes were never able to 

 traverse more than one-half the distance to the ovary. On the other hand, the 

 tubes in the crossed pistils, though starting to grow at the same rate as the 

 other, pass down the style and reach the ovary in 4 days or less. 



From these facts it is concluded that the secretions in the style stimulate 

 the pollen tubes from other plants instead of inhibiting the tubes produced by 

 pollen grains from the same plant. It is believed that there are present on the 

 style stimulants, and experiments indicate that the principal one is a sugar, 

 probably of the hexose group. In the pollen grains there is considered to be a 

 specific material in the nature of an enzym which calls forth secretion of the 

 sugar that gives the direct stimulus. 



Further observations on the relationship between the number of ovules 

 formed and the number of seeds developing" in Cercis, J. A. Harris {Bui. 

 Torrey Bot. Club, 4I {191^), No. 11, pp. 533-5Jf9, figs. //).— In a previous paper 

 (E. S. R., 31, p. 523), the author discussed the relationship between the number 

 of seeds maturing and the number of ovules formed in the pods of a series of 

 trees of C. canadensis from different habitats. 



In the present paper an account is given of collections made from individual 

 trees, in which it apiiears that the physical constants, type, variability, and 

 correlation of the number of ovules per pod and the number of seeds develop- 

 ing per pod in C. canadensis differ sensibly from individual to individual and 

 from habitat to habitat. The data do not, however, justify the conclusion that 

 trees from different habitats may be distinguished taxonomically. The correla- 

 tions for number of ovules formed and number of seeds developed per pod have 

 always been found positive and of a moderate, considerable, or even high 

 intensity. The correlation coefHcient is said to be slightly raised by the combi- 

 nation of collections from different individuals. 



The taxonomic value of pore characters in the grass and sedge rusts, J. C. 

 Arthur and F. D. Fromme {Mycologia, 7 {1915), No. 1, pp. 28-33, fig. 1). — It is 

 stated that there are at present known in North America 105 species of rusts 

 on grasses and 40 on sedges having urediniospore-pore characters that are 

 clearly distinguishable, and hence available for use in their possible application 

 to taxonomic study. Three general types of distribution of the pores are recog- 

 nized, namely, scattered, equatorial, and extraequatorial. It is thought that 

 the practical importance of pore characters of the urediniospores of the grasses 

 and sedge rusts lies in the application of this knowledge to the identification 

 of the material that is incomplete. It has already been possible to make some 

 progress in determining the species of rusts from urediniosporic material alone. 



The development of Armillaria mellea, G. F. Atkinson {My col. CentU., If 

 {191-i), No. 3, pp. 113-121, pis. 2). — This is an account of the progress of 

 differentiation in A. mellea. The view is expressed that the zone of radial 

 hyphse, and a part at least of the cortical zone of the young carpophore of 

 A. mellea, is homologous with the radial and cortical zone in Lepiota clypeo- 

 laria. It is thus homologous with the universal veil in certain species of Ama- 

 nita and Amanitopsis, but does not become differentiated from the pileus as it 

 does in these two genera. 



FIELD CROPS. 



Eeport on the experimental work of the Palur agricultural station for 

 1913-14, G. D. Mehta {Dept. Agr. Madras Rpt. 1913-14, pp. 21).— The variety 

 tests here reported include peanuts, sugar cane, and rice grown on irrigated 



