1897] MICROSCOPICAL JOURNAL 151 



J per cent sodium chloride and if a neutral or alkaline 

 medium is desired add enough of a 1 per cent solution 

 of caustic soda to bring about the required reaction. Boil 

 in a water bath for half an hour. Cool and filter through 

 ordinary filter paper and disti'ibute in sterilized flasks. 

 The amount in each flask is to be determined by the work 

 in the laboratory. I have found 500 c. c. a convenient 

 quantity. 



Preparation of nutvie^it rt^<7?'. —Dissolve 5 grams of 

 finely cut agar in about 100 c. c. of water. This may be 

 done in either of two ways, by heating over a direct flame 

 for al)out ten minutes with constant stirring to prevent 

 burning or by heating in a closed water bath until the 

 whole mass becomes gelatinous. The agar is then added 

 to 500 c. c. of bouillon, thoroughly mixed with it and 

 boiled in a water bath for twenty minutes. It is then 

 cooled down to 45° to 50"^ C. and the whites of two eggs 

 added and thoroughly mixed with the agar. It is then 

 returned to the water bath and boiled for from twenty 

 to thirty minutes. The albumen will then be collected 

 in a firm coagulum containing any insoluble particles 

 that may have been in the agar, leaving a perfectly clear 

 liquid. It is filtered while hot through ordinary filter 

 paper, the filtration taking i)lace rapidly without the aid 

 of a hot filtering apparatus. The filtrate is then distrib- 

 uted in tubes which have been previously plugged with 

 absorbent cotton and sterilized. 



Preparation of luilrient gelatin — ^To 500 c. c. of bouil- 

 lon add 50 grams of gelatin and heat in a water bath 

 until the gelatin is dissolved. Cool to about IS"" 0, and 

 and the whites of two eggs, mix thoroughly. This is 

 done most rapidly and efl'ectually by pouring the liquid 

 several times from one dish to another. Then boil in 

 a water bath for twenty minutes. Filter through ordin- 

 ary filter paper and distribute in sterilized tubes. Care 



