1897] MICROSCOPICAL JOURNAL 151 



^ per cent sodium cliloiicU' and if a neutral or alkaline 

 medium is desir(Ml 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 distril)ute in sterilized flasks. 

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

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

 quantity. 



PreparaHon of nutrient rt^^rr. —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 about ten minutes with constant stirring to prevent 

 burninir or bv Ijeatin*:; in a closed water bath until the 

 whole mass becomes geh'itiiious. The agar is then added 

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

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

 cooled down to 45° to oO"" 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 lii'ui coaguluin containing any insoluble particles 

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

 liquid. It is filtered while hot through ordinary filter 

 paper, the filtration taking jjlace rapidly without the aid 

 of a liot tilteiing appai'atus. The filtrate is then distrib- 

 uted in tubes which have been previously plugged with 

 absorbent cotton and sterilized. 



Preparati')ii of nulrieiit gelatin — To 500 c. c. of bouil- 

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

 until the gtdatin is dissolved. Cool to about 45"" C. and 

 and the white's of two eggs, mix thorougiily. Tliis is 

 done most rapidly and effectually by ])()ui-ing the li(]uid 

 several times from one dish to another. Then boil in 

 a water batli foi' twenty minutes. Filter through ordin- 

 ary filter pa[ier antl distribute in sterilized tubes. Care 



