726 CONTRIBUTIONS TO OUR KNOWLEDGE OF SOIL-FERTILITY, xiv., 



the physical structure, according to Rahn, but to the nutrients 

 going more easily into solution. 



The stimulating effect of a volatile disinfectant, such as chloro- 

 form, is not only evident in soil, but also on presumably microbe- 

 free, vegetable tissue. For example, the recent work of the 

 Armstrongs shows that many chemicals, including toluene, chloro- 

 form, ether, and carbon bisulphide, can bring about an interaction 

 between enzyme and glucoside which does not occui- in their 

 absence. The effect is probably caused by an increased per- 

 meability of the cell-walls of the tissue by the action of the dis- 

 infectant, and the consecjuent easier migration of the enzyme. 



If this applies to a collection of cells, it may also apply to a 

 single cell, such as a microbe, and the action becomes stimulative, 

 as suggested by Fred, and not only may it be stimulative for one 

 bacterial enzyme but for many. Any stimulative action will, 

 however, be restricted to one bacterial cell, and will not influence 

 the progeny of that cell, so that, under the conditions that pre- 

 vail when a soil is moistened after the removal of the disinfectant, 

 the stimulative action should rapidly disappear. One can 

 imagine an initial but not a prolonged stimulation, such as obtains 

 in treated soils. 



It is assumed that all the volatile disinfectant is dissipated 

 when no odour is observable after spreading out the soil to the 

 ail', and that none remains in the soil. An appeal to the senses 

 certainly shows that a disinfectant, such as chlorofoi-m, has all 

 evaporated. But are we justified in concluding that such is the 

 case 1 May not some be fixed by the soil-constituents ? This 

 question appears to be at the root of the stimulative action of 

 volatile disinfectants, such as chloroform, upon soil, and certain 

 experiments were made to test the validity of the contention. 



In testing the persistence of carbon disulphide in treated soil, 

 Moritz and Scherpe"^ found traces of the decomposition-product, 

 sulphuric acid, up to five months after treatment; while Heinzef 

 found it qualitatively, as carbon disulphide, at the end of a 

 month. 



*Centrlbl. f. BaUt., 216 Aht. 12, p. 573. fibid., 18, p. 62. 



