BY R. QREIG-SMITH. 637 



ture for a rapid development of toxin. The highest temperature, 

 37°, appears to show that an initial destruction of toxin occurred, 

 and that this was followed by a subsequent formation. 



Extracts from chloroformed and air-dried soils. — As a rule, 

 the extract of a soil which has been treated with a volatile anti- 

 septic, such as chloroform, is more nutritive towards bacteria 

 than untreated soil. The amount of moisture in the soil when 

 chloroformed should have some influence, and the nature of the 

 result may depend upon whether the soil has been chloroformed 

 in the natural state, or whether it has been more or less air-dried 

 to obtain a more representative sample. That the moisture has 

 an influence was shown in an experiment in which the soil, with 

 its natural moisture, was passed through a sieve with l-"^ meshes 

 to the inch, and then treated with 5% of chloroform before and 

 after being air-dried. The disinfectant was aired-off after two 

 days' contact, and extracts of the soils were made in the manner 

 which has been previously described. The extracts were seeded 

 with a suspension of Bac. prodigiosiis, and incubated for 21 hours 

 at 22° and counted. 



Water-control 



KxLractof soil, chloroformed wet 



Extract of soil, chlorofonned drv 



Bacterial growth 



100 



33,000 



216,080 



The experiment shows that the moisture in the soil hinders 

 the action of the chloroform in liberating nutritive materials 

 from the soil. 



The effect of air-drying alone upon the toxic or nutritive 

 nature of the extract obtained from the soils was investigated 

 upon three occasions. 



The results indicate that if the soil is strongly toxic, as on 

 September 1st, air-drying increases the toxicity of the extract; 



