EXPERIMENTS INITIATED IN 1909 39 



developed either in organic infusions or in solu- 

 tions containing neutral ammonic tartrate and sodic 

 phosphate, so as to try and find out which were 

 the particular combinations in the experimental 

 solutions most favourable for the growth and 

 multiplication of micro-organisms, and, therefore, 

 possibly also most favourable for their origination. 

 Such comparative trials were very necessary, be- 

 cause among the very numerous experiments made 

 with these solutions in 1906 there were many nega- 

 tive as well as many positive results ; and I was nat- 

 urally anxious to discover the means by which the 

 proportion of positive results might be notably 

 increased. 



Before speaking in detail concerning these ex- 

 periments with hermetically-sealed vessels which 

 were initiated last summer, it is necessary to call 

 attention to a very important point concerning the 

 ingredients used in the making of my solutions. 

 Of these, ammonic phosphate, dilute phosphoric 

 acid, and liquor ferri pernitratis are definite phar- 

 maceutical products, which ought to be severally 

 uniform in their composition whenever and wher* 

 ever procured. It is not so, however, with sodium 

 silicate, which is a variable commercial product. 



