ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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the latter in the neck of the cultivation flask / which contains the medium 
and growing culture 8 ; c, caoutchouc tubing connecting the tubes a and 
/ ; k , cork ring, and rn, a glass tube filled with mercury so as to make a 
gas-tight junction over c ; v is a glass beaker containing water ; this is 
placed over a small burner in connection with the gas regulator G ; T, 
thermometer. The various pieces of the apparatus having been carefully 
Fig. 49. 
sterilized the tube / is filled with the cultivation medium, the neck 
plugged with cotton-wool and the whole kept at 80-90° C. for several 
hours on at least three successive days. The medium is then infected 
and the whole apparatus connected up. The air is exhausted by means 
of the mercury pump and the gas developed by the culture removed 
from time to time. This is absorbed at once by potassic hydrate. 
