AGRICULTURAL BOTANY. 627 



The rat^s of sap flow in potted plants was found to vary from 145 to 240 

 cm. per hour, while for the cut plants it was a little higher, from 180 to 

 250 cm. per hour. Where portions of stems were killed by steam, heated wax, 

 or poisons the plants continued to take up water for a considerable time and 

 remained turgid longer than those in which the stems were cut and inserted 

 in water. 



The author found that the withering of the leaves on stems which had been 

 killed with heat was not due to a lack of water, but to the toxic action of 

 substances which had been carried to the leaves. It was also learned that 

 the longer the heated region the more rapidly the leaves withered. Leaves 

 above a steamed or otherwise heated portion of the stem did not wither in 

 the same way as those simply deprived of water, but were often discolored 

 before shriveling. A histological examination of such portions showed that 

 the protoplasts and chloroplasts resembled those under diseased conditions 

 more than those in leaves which were merely drying out for a lack of water 

 supply. 



On the substitution of assim.ilating' org'ans in plants from an anatomical- 

 biological point of view, B. Jonsson iVikariat inom Vdjctriket vid Ndrings- 

 beredning, sedt frdri Anatomisk-Biologislc Synpunkt. Lund, 1910, pp. 33). — This 

 is a preliminary and somewhat general account of a study of the phenomenon 

 of substitution of organs in plants for the process of elaboration of organic 

 food materials from inorganic sources. 



The author shows tliat such substitution occurs more frequently than is ordi- 

 narily considered to be the case and may take place in the stem, roots, or 

 flowers of diiferent species of plants. The most important substitution is, 

 however, found in the case of the stem and the least among other parts which 

 are exposed to the action of sunlight and which generally stand in a more or 

 less close relation to the reproductive phenomenon. 



Experiments upon Drosera rotundifolia as to its protein-digesting power, 

 W. J. Robinson {Torreya, 9 (1909), No. 6, pp. 109-114).— The author gives a 

 report on a series of experiments on the digestive power of the leaves of D. 

 rotundifolia, undertaken for the purpose of ascertaining whether the purer 

 proteins now available would give any different results from those obtained 

 by Darwin with tissue fragments or crude protein materials. The proteins 

 used were prepared under the direction of W. J. Gies, with the exception of 

 the nucleoprotein. 



The results of the experiments indicate the ready digestibility of dry egg 

 white, fibrin, tendomucoid, and nucleoprotein. Acid albumin, alkali albuminate, 

 and edestin were digested, but less readily than the others. Collagen and 

 elastin appeared entirely indigestible. Creatin did not cause bending of the 

 tentacles. 



The proteolytic enzyms of Drosera were found to be like those of other organ- 

 isms, able to digest some proteins and unable to digest others. 



The proteolytic enzym of Drosera, Jean White (Proc. Roy. Sac. [London], 

 Ser. B, 83 {1910), No. B 562, pp. 134-139). — Experiments have been carried on 

 to determine the nature of the proteolytic enzyms of Drosera, a number of 

 species of this plant being used. 



From the evidence attained it seems that the digestive process of the 

 proteolytic enzym present in the leaf glands of Drosera does not extend farther 

 than the production of peptones, and there seems to be no trace of other 

 proteolytic enzyms such as erepsin or trypsin. The author has made many 

 attempts to find signs of protein digestion carried to the amid stage, but has 

 always been unsuccessful. 



