184 



BIOLOGY AND TECHNIQUE 



in which some pyrogallic acid has been dissolved, is then allowed to flow 

 on to the cotton of the plug and the mouth of the tube is immediately sealed 

 by a tightly fitting rubber stopper. The cotton stopper in these cases must 

 be made of absorbent cotton; 1.5 to 2.5 c.c. of the pyrogallic acid solution 

 is usually sufficient for test tubes of ordinary size. 



For cultivation of anaerobic bacteria upon agar slants, a simple technique 



FIG. 19. WEIGHT'S METH- 

 OD OF ANAEROBIC CULTIVA- 

 TION BY THE USE OF PYRO- 



GALLIC ACID SOLUTION. 



FIG. 20. JAR FOR ANAEROBIC CUL- 

 TIVATION. 



may be applied and easily improvised in the laboratory as follows: the 

 tube of slant agar is inoculated with the infectious material in the usual 

 way. It is then, with stopper removed, inverted into a tumbler or beaker 

 containing about a gram of dry pyrogallic acid. A small quantity of a 

 five per cent or three per cent sodium hydrate solution is then run into the 

 tumbler and this is covered with a thin layer of liquid paraffin or albolin 

 before the pyrogallic acid has been completely dissolved. In this way, com- 



