342 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Nutriekt Broth. 
Nutrient 
Gelatin. 
Nutrient Agar. 
8. After ingredients are dis- 
solved, titrate; reaction pro- 
bably + 2*3 to + 2*5. 
Ditto ; 
reaction 
probably 
+ 4 • 0 to + 50 
Ditto; reaction probably 
+ 4*5 to + 4-7. 
9. Neutralise (Fuller’s method). Ditto. 
Ditto. 
To the 900 grm. of meat infusion 
(containing now peptone and 
salt also) add 900 grm. of the 
3 per cent, agar jelly described 
at head of this column. Since 
agar is neutral, the reaction is 
unchanged. 
10. Heat over boiling water (or steam) bath 30 minutes. 
11. Restore weight lost by evaporation to original weight of filtered meat infusion,. 
i.e. that on which the percentage of peptone, salt, &c., were calculated — 
1800 grm. in each case. 
12. Titrate — reaction probably + 0'3 to +0*5. 
13. Adjust reaction to final point desired — generally to + 1 ‘5 per cent. 
14. Boil 5 minutes over free flame, with stirring. 
15. Add water, if necessary, to make up loss from evaporation to 1800 grm. 
16. Filter Ihrough absorbent cotton, passing the filtrate through the filter repeatedly 
until clear. 
17. Titrate to determine whether or not the desired reaction has been maintained. 
18. Tube and sterilise. 
Preparation of Nutrient Agar.* — Dr. T. Yokote recommends the 
following method for making nutrient agar, on the ground that no 
special apparatus is required, and that the procedure is rapid and easy. 
500 grm. of minced or scraped meat free from fat or gristle are im- 
mersed in 1 litre of pure water, and the mixture thoroughly shaken up. 
The vessel is then placed on a sand-bath and heated at first slowly, and 
afterwards boiled for 1^ hours. The fluid is then filtered through paper. 
To 1 litre of the filtrate 15 grm. of powdered agar are added, and the 
mixture heated anew for about an hour, after which 10 grm. peptone 
and 5 grm. of salt are added. W hen thoroughly dissolved, the solution 
is treated with soda or caustic soda until it has a faint though distinct 
alkaline reaction. When it has cooled down to 50°, the whites of two 
eggs are added, and the whole thoroughly well shaken. The mixture is 
then heated for 1J-2 hours, care being taken that the temperature of 
the sand-bath near the flask is. not less than 110° C. During this time 
the w r ater lost by evaporation must be replaced. The next step is to 
strain the solution through an ordinary filter. The time occupied by 
filtration need not exceed 5 minutes, and the time for the whole pro- 
cedure should not exceed 6 hours. 
Nutrient Starch Jelly. f — Dr. E. F. Smith recommends a medium 
of which the following are the ingredients. (1) Three grm. of dried 
potatc-starch ard put in a test-tube along with 10 ccm. of the following 
* Centralbl. Bakt. u. Par., 1‘® Abt., xxv. (1899) pp. 379-80. 
f Op. cit., 2 te Abt., v. (1899) pp. 102-4. 
