330 EXPEEIMENT STATION RECORD. [Vol. 36 



some extent (E. S. R., 27, p. 222; 31, p. 222). The results, as tabulated and 

 plotted for the ivy, rubber tree, and laurel, are considered to afford convincing 

 evidence that transpiration is regulated by stomatal aperture. 



The perception of heliotropic stimulus in plants, Giulia Campanile (Awn. 

 Bot. [Rotne], 13 (1915), No. 2, pp. 139-1^8) .—The author states that in studies 

 with such plants as Vicia sativa, Cicer arietinum, and Diplotaxis, no constant 

 relation was found to exist corresponding to that suggested in the work of 

 Haberlandt (E. S. R., 31, p. 728) between the presence of certain lenticular cells 

 and the perception of luminous stimuli. In Colocasia esculenta and G. anti- 

 quorum the perception of light stimulus appears to reside in a minute organ of 

 the foliar lamina which is otherwise insensible to light. In case of some fleshy 

 plants where such relation seems to exist, it is said that the reaction still occurs 

 after removal of the epidermis. 



The relation between geotropic sensitivity in roots to the presence and 

 orientation of statoliths, Virginia Jacobacci (Ami. Bot. [Rome], 12 (191Jt), 

 No. 2, pp. 165-175). — Concluding a study of Cicer arietinum, the author states 

 that in case of this plant it appears evident that the presence, in the root tips, 

 of starch grains as statoliths is associated with the reception of gravitational 

 stimulus. 



Recent studies on the relation of geotropic sensitivity in roots to the 

 presence and orientation of statoliths, Virginia Jacobacci (Ann. Bot. [Rome], 

 13 (1915), No. 2, pp. 149, 150). — Having extended the study above noted to a 

 number of other plants, the author states that the roots which were geotropic 

 generally contained large numbers of statoliths. Results are given of such 

 studies as carried out with Cucurbita maxima. 



The vitality of seeds buried in the soil, W. J. Beal (Proc. Soc. Prom. Agr. 

 Sci., 36 (1915), pp. 25-27). — This report has already been noted from another 

 source (E. S. R., 34. p. 732). 



Mechanics of dormancy in seeds, W. Crocker (Amcr. Jour. Bot., 3 (1916), 

 No. 3, pp. 99-120). — Discussing theories of longevity, causes of dormancy with 

 methods of securing it, and forcing agents, the author states that dormancy in 

 seeds results generally from the inhibition of one or more of the processes pre- 

 ceding or accompanying germination. Seed coats play an important part in 

 both primary and secondary dormancy. Their colloidal nature permits their 

 easy modification by even low concentrations of a variety of agents, such results 

 having been frequently but wrongly interpreted as stimulus reactions. Regard- 

 ing germination conditions for both seeds and pollen, it is thought that the recent 

 trend of opinion is toward the need of general physical conditions and away 

 from the need of specific chemical stimuli, or even chemical stimuli at all. 



After-ripening of seeds or the changes during dormancy and finally controlling 

 germination may involve growth of the rudimentary embryo, fundamental 

 changes in an otherwise mature embryo, or chemical changes in the coats. In 

 after-ripening, there is often a complex interrelation between coat and embryo 

 changes. 



Foliar structure in some oaks having persistent leaves, G. Donati (Ann. 

 Bot. [Rome], 13 (1915), No. 2, pp. 157-16S, figs. i3).— This is mainly a com- 

 parative study of leaf structure in Quercus ilex, Q. suber, Q. occidentalis, and 

 Q. coccifera. 



It is stated that the structure apparent in the study of an individual or of 

 members of a given species varies with the age of the material and with the 

 conditions of the examination. The leaf type in a given species, while varying 

 somewhat as to its minor characters, is still fairly constant. Both internal and 

 external structures of young trees resemble those of older ones of tlie same 

 species. It is stated that while the foliar structures of Q. ilex and those of Q. 



