METHODS OF CULTIVATION. 179 



other; to introduce a minute quantity of blood 

 containing organisms directly from the veins of a 

 living animal ; to withdraw a small quantity of 

 fluid from the flask for microscopical examination, 

 etc., without any danger of contamination by at- 

 mospheric germs." 1 



A larger flask than those above described, hav- 

 ing its neck drawn out in the same way, will be 

 found the most satisfactory receptacle in which 

 to preserve a quantity of stock solution from 

 which to fill the smaller flasks as required. It is 

 well not to attempt to preserve too great a quan- 

 tity of the various organic infusions used in ex- 

 perimental work of this kind, in a single flask ; 

 as there is greater danger of the breaking down, 

 and consequent loss, of the stock, when a ves- 

 sel is frequently opened for the purpose of 

 withdrawing a portion of its contents. It is best 

 therefore to use a number of flasks of moderate 

 size, rather than a single large one. There is 

 always a saving of time and labor, when extensive 

 experiments are contemplated, in preparing a 

 considerable quantity of the various culture-fluids 

 at one time, so that there may be a sufficient 

 stock on hand in the laboratory to enable the 

 experimenter to proceed without delay with any 

 series of experiments he may have in view. The 

 writer keeps constantly on hand a supply of the 

 little flasks already described, charged with ster- 



1 Extract from a paper by the Author on " The Germicide Value of 

 certain Therapeutic Agents." The American Journal of the Medical 

 Sciences, No. CLXX., n. s., pp. 321-343. 



