32 EXPEEIMENT STATION EECOKD. 



tissues noted. In the experiments aucuba, privet, and pear leaves were placed 

 in titrated solutions of various chemicals. Where the leaves were entire the 

 changes took place very slowly, but if the margins of the leaves were cut, or 

 if fragments of the leaves were used the effect of the salts was noticeable in 

 a relatively short time. This method was found to be sufficiently sensitive to 

 show within 24 hours the toxicity of a solution containing 1 part of copper to 

 5,000,000. 



In studying alkaline salts, stronger solutions were used, and it was found that 

 the blackening of the leaves was an accurate index of the relative poisonous 

 properties of the different salts tested. 



Some effects of a harmful organic soil constituent, O. Schreiner and J. J. 

 Skinner {U. 8. Dcpt. Agi:, Bur. Soils Bill. 10, pp. 98, pis. J,, flgs. 31).— In this 

 bulletin the authors report on the effects of dihydroxystearic acid, a harmful 

 constituent of soil, upon plant growth and upon soil solutions and fertilizer 

 action. The experiments were conducted with wheat seedlings grown in cul- 

 tures containing phosphoric acid, nitrogen, and potash in various ratios, 50 

 parts per million of dihydroxystearic acid being added to each set of cultures. 



The difference between the cultures containing this acid and those without 

 the substance is stated to have been very marked. In addition to the general 

 appearance of the tops, marked changes were noticed in other parts of the plant, 

 which seems to show that the roots form on the whole a better physiological 

 indicator of toxicity than the growth of the tops. 



After describing their experiments in detail the authors summarize their in- 

 vestigations, pointing out that dihydroxystearic acid hinders the growth of 

 wheat plants when it is present in solution in pure distilled water, and that the 

 compound is also harmful in the presence of nutrients or fertilizer salts in all 

 ratios of the fertilizer elements phosphoric acid, nitrogen, and potash. The com- 

 pound was found to be more harmful in those ratios of fertilizers not well 

 suited for plant growth. It appears to be relatively much less harmful in the 

 presence of nitrogenous fertilizers than with those composed mainly of phos- 

 phates and potash. The compound was found to modify both the amount and 

 ratio of the fertilizer elements removed from soils, the ratio being higher for 

 nitrogen. Fertilizer combinations which tend to increase root oxidation are 

 deemed the best combinations to overcome the harmful effects of the acid. 



Some effects of a harmful organic soil constituent, O. Schreiner and J. J. 

 Skinner (Bot. (la.^., 50 {1910), No. S, pp. 161-181, figs. 11). — A briefer account 

 of the investigations noted above. 



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

 B. Sauton (Conipt. Bend. Acad. Bci. [Paris'^, 151 {1910), No. 3, pp. 2-U-2J,3).— 

 In studies of A. niger grown in culture media it has been found that the fungus 

 frequently did not produce spores, but the author has found that by adding iron 

 to the solution, spore production followed in a relatively short period. In cul- 

 tures of Aspergillus which had remained without spore production for 3 days 

 with no iron present in the solution, the addition of iron salt was followed by 

 the appearance of spores within 24 hours. 



The formation of the spores appears to be an accompaniment of the fixation 

 of oxygen, probably brought about through the intermediation of iron. 



Recent observations on callose, L. Mangin {Compt. Rend. Acad. Sci. 

 [Paris], 151 {1910), No. Jf, pp.. 279-283). — The author gives an account of inves- 

 tigations which show that there is in fungi as well as in other plants, in addi- 

 tion to cellulose and i^ectic compounds, a substance to which he has given the 

 name callose. 



This substance has been studied and it is found to differ from cellulose and 

 chitin in its rapid destruction in glycerin at a temperature of 300° C. and by 



