ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 1031 



Ferments and Enzyma.* — Dr. A. Hansen lias experimented on 

 the prodiicts of digestion resulting from tbe action on fibrin of the 

 secretion of the pitchers of Nepenthes. The fibrin was first heated 

 with hydrochloric acid, and then subjected to tlie action of the 

 Nepenthes-secretion, neutralized by soda-lye, and boiled with a 5 per 

 cent, solution of sodium chloride. The solution gave the reaction of 

 hemialbumose, while the filtrate separated from the albumoses con- 

 tains the peptone. The ferment of the Nepenthes-secretion may 

 therefore be termed a vegetable pepsin, though its definite projierties 

 as regards resistance to acids and to temperature have not yet been 

 determined. 



The latex of the fig, Ficiis carica, contains a substance with 

 enzymatic properties, causing a peptone-reaction in both acid and 

 alkaline solutions, coagulation of milk, an inverting diastatic action 

 on starch and glycogen, and a precipitation of casein. 



The latex of Carica Papaya was found also to contain a pepton- 

 izing enzyma, while substances of this kind appeared to be entirely 

 wanting in a large number of laticiferous plants, e. g. Euphorbia 

 Myrsinites and other Euphorbiacese, F/cms elastica, Papaver somniferum, 

 Chelidonium majus, Scorzonera, and Taraxacum. 



The author confirms the observation of Krukenberg with regard to 

 the presence of a peptonizing ferment in ^thalimn septicum, but not 

 those of Gorup-Besanez and Will with regard to a similar phenomenon 

 in the seeds of barley, vetches, and flax. 



Ascent of Sap.f — M. J. Vesque further explains his theory of 

 the cause and the course of the movements of water through the solid 

 parts of plants. The vessels he regards, from this jioint of view, as 

 elements for the purpose of carrying large quantities of water to 

 great distances, and also as reservoirs of water when the fluid which 

 they contain is rendered immobile by Jamin's chains, and to convey 

 the small pressure of the inclosed air to a distance. The ascent of 

 sap takes place in the following way. 



The transpiring cells remove water from the fibres in the upper 

 part of the plant, and the pressure of the air contained in these fibres 

 consequently decreases, and they absorb water from fibres below 

 them. The distribution of the air and water in each fibre depends on 

 capillary attraction ; each change in the volume of water corresponds 

 to a new arrangement of the gaseous and liquid fluids, causing water 

 to be carried to the upper part of the cell along its walls, the coll 

 itself having previously contained water in its lower part only. This 

 is brought about by capillarity only ; the layer of water which covers 

 the inside of the wall of the fibre and separates it from the air-bubble 

 does not press by its weight on the fluid column, but on the skeleton 

 of the tree ; in consequence of which the pressure of water on the 

 base of the tree is not greater than that of the smn of the indices of 

 water which vary in tlic body of the tree ; and these cannot exceed 



* Arbeit. Bot. Inat. "Wijrzburg. iii. (1885) pp. 253-88. 



t Ann. Agronomiqur-8, xi. (1885) p. 214. SSec Nattirforsolicr, xviii. (1885) 

 p. 300. Cf. this Journal, iv. (1884) p. 85. 



'.) X 2 



