240 



METHODS .OF CULTIVATION 



3 . By means of a pipette drop about i c.c. of pyrogal- 

 lic acid 10 per cent, aqueous solution on to the plug. 

 It will immediately be absorbed by the cotton- wool. 



4. With another pipette run in an equal quantity 

 of the caustic soda solution. 



5. Quickly close the mouth of the tube with a tightly 

 fitting india-rubber stopper. 



6. Incubate. 



Method VIII (McLeod's Method). 



Apparatus and Solutions Required. 



McLeod's plate base (a hollow glazed earthenware disc 9 cm. in 

 diameter and 2 cm. deep: the upper surface is pierced by a central 

 hole, 2 cm. in diameter, giving access to the interior, the lower 

 part of which is divided into two by a low partition. A shallow 

 groove encircles the upper surface near to the edge) . 



FIG. 131. McLeod's anaerobic plate base with half petri dish inverted 



in situ 



Plasticine. 



Pyrogallic acid (i gramme) compressed tablets. 

 Sodic hydroxide (0.4 gramme) compressed tablets. 

 Wash bottle of distilled water. 



Surface plates of one or other agar medium (in petri dishes of 

 8 cm. diameter). 

 Surface plate spreader. 



METHOD. 



i. Roll out a long cylinder of plasticine and fit it 

 into the groove on the upper surface of the earthenware 

 base. 



