AGKICULTrUAL IJOTANY. 737 



is fdi-nu'tl, Imt the funjius doi-s not oxloiul its attack iiitu tbo inner layers of 

 the cortex. At 3S° no infection can be secured. 



The influence of temperature on the action of poisons, L. Zehl (Ztschr. 

 \Uii. I'ln/sioL, S (HWS), /)/>. I.',0-W0; abs. in Hot. CvntbL, JOS (1908), A'o. 13, 

 lip. 3^S, ,U!)). — A series of experiments witli spores of AHixrgiUuH nigcr and 

 rcnicilliiiiii (jlnucnin were conducted to determine the poisonous action of a. 

 nnmlier of inor^'inic and organic compounds. Anions; the inorganic compoimds 

 used were aluminium suli)liate, coi)alt, copper, lithium, nickel, and zinc, as well 

 as boracic acid and potassium chromate. Of tlie organic compounds, ethyl 

 alcohol, amyl alcohol, chloral hydrate, acetanilid, antipyrin, phenol, picric acid, 

 etc., were used. 



The author found that raising the temperature increased the poisonous 

 action (if the inoriranic compounds when used singly. In most cases the in- 

 crease amounteil to o times the initial toxicity, but for temperatures between 

 ;'>0 and 40° ('. there was found to be no correlation between increased toxicity 

 and increase in temperature, the toxicity increasing much more rapidly than 

 the temperature. The organic poisons acted in a similar manner. No definite 

 cause for this action could be determined, but the author believes that it can 

 not be wholly explained by the increased ionization of the salts at the higher 

 temperatures. 



Where combinations of 2 inorganic salts were added to the culture media, 

 the toxicity of the combined poisons was less than where the single salts were 

 used. Where 2 organic or an organic and an inorganic i)oison were tested, the 

 results were (piite variable, the relative toxicity being increased in some cases 

 while it was diminished in others. 



Studies on germination and plant growth, 8. I'. 1'ickkrino (Jour. Agr. 

 Sci., 2 (1908), No. .'i, pp. J/ll-'iS'i). — According to the author, experiments have 

 iieen in progress at the Woburn Experimental Fruit Farm on the effect of grass 

 on trees, which have led to the conclusion that this effect can not be attributed 

 to root competition, increased evaporation, differences in temi)erature. aeration, 

 etc., but is due to some poisoning action exerted by the .grass. Whether such 

 action is a direct result of the growth of the grass, or an indirect one operating 

 tlirough the. medium of soil bacteria, is the subject of the investigations here 

 described. 



The germination of a number of different kinds of seeds in heateil soil seemed 

 to indicate that the detrinient.-il action of the grass can not be attributed to 

 bacteria. Soils which were heated without drying to temperatures of from 

 (><»" to l.">0° behaved unfavorably toward the germination of seeds, n'tarding 

 and in most cases decreasing the total germinations. Sterilized seeds with 

 and without inoculation behaved in the same way as unsterilized ones, and, 

 aiccfU'ding to the author, the retarding effect of germination produced by heating 

 the soil can not be explained by an alteration in the bacteria! condition of the 

 S4iil, for the alteration extends progressively at temperatures beyond that 

 siitHcient to destroy all bacteria. 



By heating the soil an increase in the soluble constituents w.is found to 

 occur, especially in the soluble organic antl nitrogenous matter, and the increase 

 of either of these was foinid to be directly jiroportional to the increase in the 

 lime recjuired for germination. The increase in the sciluble constituents ap- 

 pears to 1)0 due to the formation of a nitrogenous compound in the soil, which 

 is inhibitory toward germination. Tills comi)ound is sutliciently stal)le for 

 extraction in solution, and it does not seem to be destroyed when the soil con- 

 taining it Is kept at ft low atmospheric temperature for some months. The 

 Inhibitory substance is not of an acid nature, and the experiments do not 

 settle definitely whether any of it is lu-esent lu the soil before lieatiug, but it 



