AGKICULTUBAL BOTANY. 529 



marked after 30 days in case of Penicillium variable in cane sugar solution witti 

 ammonium sulphate as the nitrogen source. 



Copper treatments and nitrification in the soil, G. Paturel (Prog. Agr. et 

 Vit. (Ed. VEst-Ccntre), SJf (1913), No. 23, pp. 711-71^).— In experiments bear- 

 ing upon the question whether the copper treatments used against cryptogamic 

 diseases may not be detrimental to the process of nitrification, the author 

 claims to have shown that the presence in the soil of copper salts from such 

 treatments opposes no important obstacle to nitrification. It is stated in ex- 

 planation that the copper salts introduced into the soil rapidly take an insoluble 

 form in the presence of carbonate of lime and oxids of iron and of aluminum. 



The effects of poisons at different concentrations upon seeds, V. Arcichov- 

 SKij (Biochem. Ztschr., 50 (1913), No. 3-4, pp. 233-2U, pi. 1, figs. 5).— From a 

 study of the influence of several poisons on seeds, the author concludes that the 

 markedly nonpoisonous influence of very high concentrations is a phenomenon 

 of a general character but limited in its manifestations by the low solubility 

 of some poisons. The causes of this result, it is thought, may be complicated- 

 including such factors as (1) the slow or slight penetration of the stronger 

 solutions of the poisons employed, (2) the lowered chemical activity of the 

 dried seed protoplasm, and (3) the lowered relative and absolute dissociation 

 of these poisons when in strong solutions. It is thought that in case of non- 

 electrolytes, polymerization may play an important part. Further researches 

 are contemplated regarding these points. 



Toxicity of smoke, L. I. Kjjight and W. Crocker (Bot. Oaz., 55 (1913), No. 

 5, pp. 337-371, figs. 4). — In a series of experiments to determine the reliability 

 of the etiolated epicotyl of the sweet pea as a test for the presence of traces of 

 heavy hydrocarbons in the atmosphere, the authors extended previous work 

 (E. S. R., 29, p. 132) and made a study of the response of this organ to smoke 

 produced by the burning of various carbon-bearing substances, with the idea of 

 discovering the constituent or constituents that produce this response. The 

 substances used included smoke from tobacco, cigars, and cigarettes, smoke 

 from cellulose paper smoked as a cigarette, etc. 



In the case of cigar smoke washed with sulphuric acid and sodium hydroxid, 

 1.000 parts per million of atmosphere produced a triple response in the epicotyl 

 of the sweet pea, resulting in the reduction of the rate of elongation, swelling, 

 and diageotropism of the portion growing in the impurity. On the basis of 

 drj' weight burned, the washed smoke from cellulose paper cigarettes was even 

 more toxic. 



Cellulose paper smoked as a cigarette and burned as an open sheet were com- 

 pared, and it was found that the former was 50 times as toxic as the latter, 

 the higher oxygen supply during burning evidently reducing toxicity. 



In the cigarette smoke of cellulose paper, the authors found carbon dioxid, 

 carbon monoxid, acetylene, ethylene, methane, and some higher homologues of 

 the last three. It is believed improbable that acetylene and propylene play 

 any part in the toxicity of paper smoke, and the great toxicity of ethylene 

 makes it probable that it determines the toxic limit. 



In addition to the gases mentioned above, tobacco smoke bears hydrogen 

 sulphid, ammonia, nicotin, hydrocyanic acid, and P3Tidin. None of these pro- 

 duced the type of response caused by the smoke, and it is considered that 

 they exist in concentrations far below that necessary to determine the toxic 

 limit. 



The etiolated epicotyl of the sweet pea was found to be a very delicate test 

 for the hejivy hydrocarbons, such as ethylene, exceeding by many fold the 

 delicacy of any chemical test. 



A bibliography is appended. 



