APPARATUS, MATERIAL, AND REAGENTS. 625 



A liberal supply of test-tubes should always be kept in stock, as 

 they are not only employed for the tube- cultivations, but can be 

 conveniently used for storing bouillon, sterilised water, etc. 



Cylindrical glasses graduated in cubic centimetres, 10 ccm., 100 

 ccm., 500 ccm., are required for measuring the liquid ingredients 

 of nutrient jelly, and also in preparing the various staining 

 solutions. 



A large wide-mouthed glass jar, with a glass cover, is extremely 

 useful. It must be padded at the bottom with cotton wool for 

 containing a stock of tubes of sterilised nutrient jelly, and should 

 be placed within reach on the working table. 



Balance and Weights. — A balance, with large pans and set of 

 gramme weights, is constantly required. 



Cotton Wool. — The best or " medicated " cotton wool should be 

 procured. 



Gelatine. — The gelatine for bacteriological purposes must be of 

 the very best quality (gold label). 



Agar-agar. — This is also called Japanese Isinglass ; it consists 

 of the shrivelled filaments of certain Algae (Gracilaria lichenoides 

 and Gigartina speoiosa). 



Peptonum Siccum. 



Table Salt. — Prepared table salt can be obtained in. tins or 

 packets. 



Litmus Papers. — Blue or red litmus paper in cheque-books, for 

 testing the gelatine mixture, etc. 



Carbonate of Soda. — A bottle, containing a saturated solution 

 of carbonate of soda, and provided with a pipette stopper, may be 

 kept, especially for use in the preparation of nutrient jelly. 



Lactic Acid. 



Filter Paper. — For filtering gelatine, stout Swedish filter paper 

 of the best quality is recommended. 



Flannel or Frieze. — This is employed as a substitute for, or 

 combined with, filter paper in the preparation of nutrient agar- 

 agar. 



(H) Apparatus for Employment op Nutrient Jelly in Test-tube 

 AND Plate-cultivations. 

 Wire Cages. — These cages or crates are used for containing 

 test-tubes, especially when they are to be sterilised in the hot-air 

 steriliser ; or for lowering tubes of nutrient jelly into the steam- 

 steriliser, etc. (Fig. 254). 



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