METHODS OF CULTIVATION. 175 



from dust, and the contained fluid is less liable to 

 contamination when the outer layer of cotton- 

 wadding is removed for any purpose. It is well 

 to carbolize the cotton-wadding used for the outer 

 protective cap, as recommended by Lister. This is 

 done by soaking it in a solution of one part of crys- 

 tallized carbolic acid in one hundred parts of anhy- 

 drous ether, after which it is allowed to dry. 



Lister has shown that organic infusions may be 

 kept indefinitely, without undergoing change, in a 

 wine-glass covered first with a watch-glass, and 

 then with a glass shade as shown in Fig. 3. The 

 apparatus, as arranged in the figure, is purified by 

 being introduced into a hot oven ; and after it has 

 cooled, the sterilized fluid is introduced from a 

 large, double-necked stock-bottle, seen in Fig. 4. 

 To do this, the cotton cap is removed from the 

 nozzle of the stock-bottle, and the half of a rubber 

 ball, having an opening in the centre, is attached to 

 its extremity. This rubber hemisphere, which has 

 been previously sterilized by soaking it in a strong 

 solution of carbolic acid, serves the purpose of 

 covering the mouth of the wine-glass when the 

 glass cover watch-glass is removed. 



Culture-Flasks used ~by the Author. The writer 

 described, in a paper read at the meeting of the 

 American Association for the Advancement of 

 Science, in August, 1881, a method of conducting 

 culture-experiments which he has found extremely 

 satisfactory, and which has the advantage of as- 



