1020 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Torula is even but very slightly sensitive to hydrocyanic acid ; and the 

 alcoholic fermentation of grape-sugar goes on unaffected even by a 

 2 per cent, solution of chinolin. 



Even in the same organism, the resistance to external agents often 

 varies greatly. Both the Saccharomycetes and Schizomycetes endure 

 a higher temperature than most algae, but die more quickly in an 

 alkaline silver-solution. As a general rule, the resistance decreases 

 with a rise of temperature ; while a lower temperature retards the 

 vital movements, and thus increases the power of resistance. 



Peculiar Structure of Protoplasm in the Paratracheal Paren- 

 chyma.* — Dr. E. Giltay describes a peculiar structure of the proto- 

 plasm in the layer of small, often very irregular and lignified, 

 parenchymatous cells which surround the large vessels with bordered 

 pits in the stem of Bryonia dioica. It consists in a differentiation of 

 the outer layer of the protoplasm of these cells into closely packed 

 rods, very difficult to detect without staining, but rendered very 

 evident by the deep staining from hsematoxylin. Other reagents 

 produce no effect on them. The author suggests that their fxmction 

 may be connected with the conduction of water. 



Tannin and Lignin in Galls.f — According to Herr C. Hartwich, 

 the starch which is found in abundance in the nutritive layer of 

 Infedoria-gslls is not used directly for the nutrition of the larva, but 

 undergoes in the first place transformation into other substances. 

 Among these are round or irregular bright brown-red balls of tannin, 

 not exceeding 30 /x in diameter ; and among them, but not so common, 

 peculiar colourless or yellowish bodies, usually of an ovoid form, 

 which he has determined to consist chiefly of lignin. 



Conditions of the Development and of the Activity of Chloro- 

 phyll.J — Dr. J. H. Gilbert gives an account of some experiments made 

 in conjunction with Dr. W. J. Eussell, which show a close connection to 

 exist between the formation of chlorophyll and the amount of nitrogen 

 assimilated by plants ; the amount of carbon assimilated is not, how- 

 ever, in proportion to the chlorophyll formed, unless a sufficiency of 

 mineral substances, required by the plants, is available. In cases 

 where both nitrogenous and mineral manures were applied, a lower 

 proportion was observed of nitrogen assimilated and chlorophyll 

 formed over a given area, which is no doubt due to the greater assimi- 

 lation of carbon and consequent greater formation of non-nitrogenous 

 substances, although the amounts of nitrogen assimilated and chloro- 

 phyll formed were as great, if not greater. 



Sieve-tubes in the Leaves of Dicotyledons.§ — Dr. A. Fischer 

 gives the following as the results of a number of observations. 



The width of the sieve-tubes, and of their accompanying cells, 

 decreases with the diameter of the veins of the leaves ; but the sieve- 

 tubes decrease in width much more rapidly than the accompanying 



♦ Nederl. Kruidk. Arch., 1S84, p. 187. See Bot. Centralbl., xxii. (1885) p. 199. 

 t Ber. Deutsch. Bot. Gesell., iii. (1885) pp. 146-50 (1 pi.). 

 X Nature, xxxii. (1885) p. 539. (Paper read before the British Association, 

 Section B.) 



§ Ber. Verhandl. K. Sacha. Gesell. Wiss., 1885, pp. 245-90 (2 pis.). 



