.1020] AGRICULTURAL BOTANY. 525 



seedlings showed a spneral tendency of the plant to adjust the reaction to a 

 point slightly below neutrality. Germination of the seed was found less sensi- 

 tive to an acid reaction in wheat, corn, soy bean, and alfalfa than was the 

 subsequent growth of the see<lliiig. The rea<tion of different concentrations 

 toward germination is shown. 



Growth curves, A. Uii'I'KI, (lirr. Dcul. Hot. CckcU., 37 (1919), No. 3, pp. 169- 

 175, fig. 1). — It is thought safe to conclude that growing protoplasm passes 

 through a period of activity si»ecilic for both organ and individual The cours'j 

 of this is determined by physico-chemical laws and is of the same order as a;i 

 autocatalytic reaction, being influenced only collaterally and quantitatively by 

 external factors. 



Regeneration of tendril tips and contact sensitivity in twining plants, 

 n. LiiKFLKu {licr. Dcut. Hot. arscU., 37 (1919), No. 1, pp. 6-2J,, figs. 8).— The 

 results are indicated of studies on such plants as PhaHcoJnn multifiorus, P. vul- 

 garis, ]'. tvukiricn.^is, JIumnJuK lupulux, Dio'icorea sativa, and Hexaccntris 

 mysorenxia, as regards the effects on growth and movement of various factors 

 which are indicated. 



[The function of latex vessels], C. Simon (Hot. Centbl, Bcihefte, 35 (1918), 

 1. Abt., No. 2, pp. 183-218). — Studies on species of Papaver and Euphorbia as 

 described are said to show that certain coloring matters are alundantly de- 

 posited in the latex vessels, though these vessels may remain imcolored in spite 

 of the high coloring produced in neighboring tissues. The latex tubes are 

 probably not to be regarded as organs of transference. 



Recent notes on the nutritive layer of the pollen, MascriS (Compt. Rend. 

 Acnd. .SV/. [Pahs], 168 (1919), No. 2/f, pp. i2///-12i6).— Studies previously re- 

 ported (E. S. R., 42, p. 819) are said to have been confirmed by studies on 

 Datura stramonium and D. tatula, the order of the occurrence of the phenomena 

 being the same in each case. Observations on other species are noted. The 

 existence of chondriomes was established for all the genera studied. Starch 

 was always present, in the form of very small grains. Fats were abundant in 

 certain .species named. Tannoid and alkaloid bodies (both presumably waste 

 materials) were present in the nutritive layer of the pollen grains of certain 

 species. 



Two crystalline phospho-organic salts in green plants, S. Posternak 

 (Compt. Rend. Acad. Sci. [Paris], 168 (1919), No. 24, pp. 1216-1219, fig. /).— 

 The author gives a descriptive .iccount of th.; preparation of two crystalliiie 

 phospho-organic salts for use in connection with the study of phospho-organic 

 reserves in green plants. 



The formation of soluble starch in elective nitrogen metabolism, F. Boas 

 (Per. Dcut. Hot. (Icscll., 37 (1919), No 1, pp. 50-56) .—T\\q general significant 

 difference between anuuonium chlorid and other nitrogen yielding compounds 

 (tested with Aspergillus niger) is that the latter are less readily dissociated. 

 The significance of certain implications in this connection is discussed. 



Studies on the assimilation of carbon dioxid, R. Wit.lstattkr and A. 

 Stoi.i. (Untersuchungcn iibcr die Assimilation der Kohlcnsdure. Berlin: Julius 

 Hpringer, 1918, pp. VllJ+Jf/fS, pi. 1, figs. 16). — This collection, comprising con- 

 tributions on assimilation by plants of carbon dioxid, is in seven main sections, 

 dealing respectively with the constancy of chlorophyll content during assimila- 

 tion; the relation between assimilatory performance by the leaves and their 

 chlorophyll content; absorption of carbon dioxid through unilluminated leaves; 

 the behavior of chlorophyll toward carbon dioxid ; the constancy of assimilatory 

 coefTicients during increased assimilation; the dependency of assimilation uimn 

 the presence of small amounts of oxygen ; and studies on intermediate stages iu 

 assimilation. 



