C. GELATIN. 



1. Make meat-water as above, under A 1 and 2. 



2. Salt, 5g. 



3. Peptone, lOg. 



4. Gelatin, lOOg. 



5. Heat in water-bath to 50 degrees until the gela- 

 tin is dissolyed. 



6. Make slightly alkline. 



7. Boil three-quarters to one hour.* 



8. Filter. 



D. AGAR-AGAR. 



1. Make bouillon (See A and B). 



2. Add 10 to 20 g. agar-agar, finely cut up. 



3. BoU until the agar is dissolved (five to eight 

 hours). 



4 Neutralize if necessary and add glycerin if de- 

 sired. 



5. Boil from three-quarters to one hour. 



6. Filter (filtration is often rapid at room-tempera- 

 ture, but if it should occur slowly the agar must be 

 filtered in steam or in a hot- water filter). 



E. AGAR-AGAR GELATIN. 

 This medium is prepared as indicated above, using, 

 however, only 7.5g. of agar, and, when this is dissolved, 

 adding 50g. of gelatin. 



F. PREPARING THE PEPTONE MEDIA WITH 

 LIEBIG'S MEAT EXTRACT. 

 Instead of using chopped meat, Liebig's Meat Extract 

 may be substituted in the proportion of from 3 to 5 

 grammes to the litre of water. 



G. BLOODSERUM. 



(Ascitic and hydrocele fluid often contain too little albnicen to ad- 

 mit of coagulation. Such fluids shonid therefore be tested by boil- 

 ing before tubing.) 



1. Collect the blood in large jars, which can be closed 

 tightly, and close the jars. 



2. In about fifteen minutes, or after clotting has 

 begun, pass a sterilized glass rod around the clot, be- 

 tween its surface and the wall of the jar, thus breaking 

 up the glass adhesions, which prevent the clot from 

 sinking. 



. 3. Again close the jars and place them in an ice- 

 chest, for from twenty-four to forty-eight hours. 



lOne must be cautioned against too long boiling of the solution, 

 since tiis lowers the solidifying point of the gelatin. 



55 



