630 EXPERIMENT STATION EECORD. 



darkness and from the fact that latex contains a number of compounds, such as 

 sugars, starch, fats, and albuminoid substances, he believes that latex plays an 

 important role in the nutrition of the plant and is not to be considered a waste 

 product. 



Tests for tannin in the living plant and the physiological significance of 

 tannin, C. van Wisselingh (E. Akad. Wetensch. Amsterdam, Proc. Sect. 8ci., 

 12 (1910), pt. 2, pp. 6S5-705). — ^A description is given of a method of demon- 

 strating tannin in living plants by means of solutions of antipyrin and cafCein 

 used as microchemical reagents. The tannin is precipitated and its abundance 

 Is estimated from the color and amount of the precipitate. 



In studying the function of tannin, experiments were made with Spirogyra, 

 and it was found that cell division and cell-wall growth ceased when the tannin 

 had been precipitated. On this account it is believed that tannin must serve 

 as a plastic substance in the building up of cell walls. 



In conclusion the author states that tannin in the plant studied is not a re- 

 serve material but belongs to the soluble substances which the plant continually 

 requires for its development. It disappears and gives way to reserve material 

 when the plant forms zygospores and passes into the resting condition. 



The effect of acids, alkalis, and some inorganic salts on plants, K. K. 

 Gedroits (Zhur. Opytn, Agron. (Russ. Jour. Expt. Lanclw.), 11 (1910), Nos. J^, 

 pp. 5U-518, figs. 3, dgm. 1; 5, pi). 6J1I-6I8, fig. i).— Studies are reported by 

 which the author sought to determine the lowest concentration of certain com- 

 pounds that would result in the death of plants and also the highest concen- 

 tration they could withstand without injury. The plants, which were flax, 

 mustard, vetch, alfalfa, oats, and barley, were grown in water cultures and the 

 effects of the following acids, alkalis, and compounds were tested: Nitric, 

 hydrochloric, sulphuric, phosphoric, acetic, and citric acids, caustic potash, 

 magnesium chlorid, potassium nitrate, calcium nitrate, potassium sulphate, 

 potassium chlorid, magnesium sulphate, and a saturated solution of calcium 

 sulphate. 



Flax was found most susceptible to the action of the acids, followed by mus- 

 tard, vetch, and barley in the order named. With the alkali, flax and mustard 

 showed the least limit of resistance and oats and barley the widest variation. 

 In their relation to the limits of high and low concentrations of the salts used, 

 all the plants were very similar in their behavior. 



The plants were found to be readily divided into two groups, mustard and 

 flax being somewhat the most susceptible, with vetch, alfalfa, oats, and barley 

 following in the order named. Arranging the salts according to their injurious 

 action, magnesium sulphate ranked first, followed by magnesium chlorid, potas- 

 sium sulphate, and potassium chlorid, with calcium nitrate and potassium 

 nitrate the least injurious. 



The influence of iron on the formation of spores in Aspergillus niger, 

 G. LiNOSsiEE (Com^t. Rend. Acad. Sci. [Paris], 151 (1910), No. 23, pp. 1075, 

 1076). — The author comments on a previous article (B. S. R., 24, p. 32) relat- 

 ing to the influence of iron on the formation of spores in this fungus, and calls 

 attention to an earlier publication in which he has shown that iron is a con- 

 spicuous constituent of the coloring matter of the fungus without which there 

 is no spore formation. 



On the death of plants from low temperatures, A. Richtee (CcntU. Bakt. 

 [etc.], 2. AM., 28 (1910), No. 25, pp. 6 17-62 J,) .—The results of low temperature 

 experiments with AspergiUvs niger are given, in which the mycelium of this 

 fungus was subjected to freezing temperatures for 24 hours by means of a 

 mixture of ether and carbon dioxid, and then thawed. 



