APPARATUS FOR ANAEROBIC CULTURE 65 



opening in the middle. The interior of each capsule is divided into two 

 halves by a partition which, however, does not extend the whole way up ; 

 in one half, solution of pyrogallic acid is placed, in the-other, solution of 

 potassium hydrate. Plasticine is placed round the margin of the upper 

 surface of each capsule. Plate cultures having been made in glass dishes 

 in the usual way, each dish is inverted and placed over a porcelain 

 capsule and carefully fixed in the plasticine. When this has been done, 

 the two fluids in the capsule are mixed by tilting and -the oxygen in the 



c 



D 



Fig. 20. — M'Leod's capsule for anaerobic plating, shown in section. 



interior is rapidly absorbed. Another improvement is that the edges of 

 the glass dishes which rest in the plasticine are turned up so as to prevent 

 the condensation water from running over the plasticine (Fig. 20, b). 



Henry's Method. — In this modification two shallow circular dishes 

 (portions of Petri capsules) are separated by a tin diaphragm, in the 

 centre of which is an aperture (Fig. 21). The upper dish contains the 

 plate culture, the lower (smaller) contains pyrogallic crystals. Grooves 

 are present in the metal to receive the margins of the dishes, which are 

 fixed in with plasticine. The lower dish is first fixed in position, and 



Fig. 21. — Henry's apparatus. 



just before the upper dish is adjusted, 10 c.c. of caustic potash are run 

 into the lower through the opening in the plate. 



' It is often advisable in dealing -with material suspected to 

 contain anaerobes to inoculate an ordinary deep glucose agar 

 tube with it, and, incubating for 24 or 48 hours, to then apply an 

 anaerobic separation method to the resultant growth. Sometimes 

 the high powers of resistance of spores to heat may be taken 

 advantage of in aiding the separation (vide Tetanus). 



Cultures of Anaerobes. — When by one or other of the above 



5 



