AGRICULTURAL BOTANY. 127 



rose apple. The mango, which is recognized as a very important fruit in the 

 Tropics, is heing studied with a view to securing improved varieties, but in con- 

 nection with breeding experiments the possiblity of several embryos must be 

 considered. 



The effect of acids, alkalis, and neutral salts on the fermentative activity 

 of yeast cells, E. Dkauulp: and Dais'y (i. Scott ( Bio-Chcin. .lour.. 2 (J907), 

 No. 7-8, pp. S-iOS-'tO, dgm. 1). — An account is given of observations on the effect 

 of acids, alkalis, and neutral salts on the rate of fermentation induced by yeast 

 cells and also some notes on the rate of multiplication of yeast cells in culture 

 media to which a neutral salt had been added to increase the osmotic pressure. 

 The solutions employed were sodium chlorid, potassium chlorid, sodium nitrate, 

 potassium nitrate, hydrochloric acid, nitric acid, sodium hydroxid, and potas- 

 sium hydroxid. all of which were made up in various fractional portions of 

 gram-molecular strength. 



The neutral salts failed to exercise any marked inhibiting action on the fer- 

 mentative activity of yeast when added to sugar solutions in strengths of 0.1, 

 0.01, 0.001, and 0.0001 gram-molecule. Sodium and potassium hydroxids of 

 0.1 gram-molecular strength entirely prevented fermentation. The weaker 

 strengths depressed the action, while 0.0001 affected the process but little. 

 Hydrochloric and nitric acids of the weaker strengths depressed the action of 

 yeast and at 0.1 strength entirely prevented fermentation and completely 

 inliibited the reproduction of yeast. The lower concentrations permitted slight 

 reproduction of the cells. In all strengths of the neutral salts employed the 

 cells reproduced actively. The hydroxids were found to be destructive at a 

 concentration of 0.1 gram-molecule and at this strength prevented any repro- 

 duction. At the lower concentrations, except 0.01 per cent potassium hydroxid, 

 reproduction took place. 



In a series of cultures containing sodium nitrate of strengths differing by 

 one-tenth from 1.0 to 0.1 gram-molecule the greatest reproduction was found in 

 the media containing 0.2 sodium nitrate. From this stage increasing strengths 

 of the salt depressed the activity until no reproduction took place at 0.7 per 

 cent. At greater strengths than this the solutions proved destructive to some of 

 the cells. 



Recent investigations on the development of the ascomycetes, P. Claussen 

 {Ber. Dent. Bat. GeselL, 24 (1906). Geiieralversammlioifjs-Hcft, pp. 11-38. figs. 

 7). — A review is given of some of the more recent literature relating to the life 

 liistory of the ascomycetes. A bibliography of about 100 titles is included. 



Utilization of nitrogen in air by plants, II, T. .Jamieson (Agr. Research 

 Assoc. [Scot.] Rpt. 1906, pp. 29-117. pis. 2; ahs. in Chem. Neics, 95 {1907). No. 

 2JpJi, p. 203). — Experiments are reported upon that were conducted to prove 

 that plants take up nitrogen from the air by means of special trichomes, called 

 by the author " albumin generators," which were described in a previous commu- 

 nication (E. S. R.. 18, p. 12.5)., 



Cultures were made in pots as well as water cultures with rape, cress, frogbit, 

 azolla, chickweed, and mimulus, which are reported upon in detail. It appears 

 that gains in nitrogen were made by each of these plants. Expressed in per- 

 centages of dry weight the gains were as follows : Rape .3.098. cress 2.693, 

 frogbit 2.10.5, azolla 1.87G, chickweed 0..541, and "mimulus 0.392 per cent. The 

 details of the analyses are given in an ai)pendix to the report. 



Root action and bacteria, S. Pickering (Nature [London], 76 (1907), No. 

 1902, pp. 126, 127).— In previous publications (E. S. R., 15, p. 474) it is shown 

 that injurious effects followed the growing of grass over the roots of freshly 

 planted ajtple trees at the Woburn experimental fruit farm. The conclusion at 

 that time was that the effect was due to a poison produced either directly by the 



