AGRICULTURAL BOTANY. 533 



and tlien thoroughly washed in a weak solution of common salt. This treat- 

 ment, it is claimed, completely destroyed all the external spores of fungi and 

 bacteria on the grain, but did not appreciably injure the vitality of the seed 

 provided the seed coats were sound and unbroken. 



The influence of temperature on the respiration of higher plants, J. Kuypeb 

 {Rec. Trav. Bat. Neerland., 7 (1910), pp. 131-240, i)ls. 3, figs. 12; abs. in E. 

 Akad. Wetensch. Amsterdam, Proc. Sect. 8ci., 12 (1909-10), pt. 1, pp. 219-227, 

 pi. 1, figs. Jf). — The author has investigated the influence of temperature on the 

 respiration of some of the higher plants in order to test the theory of Black- 

 man and Matthaei regarding the limiting factors of respiration (B. S, R., 17, 

 p. 234). The experiments were made with pea, wheat, and lupine seedlings, 

 and the carbon dioxid liberation was taken as a measure of respiration. 



In general the limiting factor of temperature was found to hold good, as 

 described by Blackman, but some fluctuations were noted. The author found 

 that the temi^erature at which the harmful effect arises is higher when the 

 starch content is higher and lower in proportion as the protein content is in- 

 creased. There is believed to be an indication that the course of respiration 

 depends upon the presence of proteolytic or diastatic enzyms. The falling off 

 of respiration at a lower temperature in seeds with a high protein content is 

 believed to be connected with the fact that the optimum for proteolytic activity 

 generally lies lower than for diastatic action. 



Studies on the influence of low temperatures on plant cells, E. Schaffnit 

 (Mitt. Kaiser Wilhelms Inst. Lwndw. Bromberg, 3 (1910), No. 2, pp. 93-115, 

 figs. 2). — The effects of low temperatures on the cell sap, chemical constituents, 

 enzyms, physical changes, and death points of green plants, spores, and pollen 

 grains are discussed. 



It is claimed that temperatures near the freezing point produce in plant cells 

 chemical products which represent a transition of the less stable compounds 

 into the more stable forms and have a certain economic significance. 



The death point of plants from cold varies according to the type of plant or 

 organ. For those to whose constitution and existence water is an absolutely 

 essential factor, the abstraction of water is the primary cause of death, while 

 chemical and physical changes produced by low temperatures may be con- 

 sidered as secondary factors. For plants and plant organs which can and do 

 exist for long periods without much water, such as lichens, mosses, seeds, 

 spores, etc., the death point varies for each individual case. 



The conclusion is therefore reached that for a given temperature death re- 

 sults from vital reaction processes called forth by the external influences. 



Contribution to the knowledge of water secretion in plants, W. Bueck 

 (K. Akad. Wetensch. Amsterdam; Proc. Sect. Sol., 12 (1909), pt. 1, pp. 306- 

 321; 400-J,17).—In a previous paper (E. S. R., 22, p. 329) the author pointed 

 out the biological significance of the secretion of nectar in flowers. The in- 

 vestigations upon which these conclusions were based led to an examination 

 of water secretion from different surfaces of the plant. 



The current belief is that many herbaceous plants and shrubs secrete drops 

 of water during the night and early morning, due to the root pressure. The 

 author has examined a considerable number of plants representing many species 

 and arrives at the conclusion that in considering the secretion of water on the 

 surface of the plant we must not only take into account the formation of drops 

 which result directly from root pressure, but also that which is brought about 

 on the apex and margin of the leaves and the leaf surfaces as a result of the 

 action of glands. In many cases these glands are originally mucilage cells, 

 but in other cases they are really water glands. 



