46 BACTERIOLOGY 



modified by the admixture of about 6 per cent, of pure 

 neutral glycerine. It has lately been shown by Nocard 

 and Roux that tubercle bacilli and the bacilli of glanders 

 flourish very freely on a nutrient medium so made. 



Kowalski prepares both nutrient gelatine and nutrient 

 agar in the following way : Instead of meat, a kilogram of 

 calf's lung is used in the preparation of the broth. It is 

 cut up, two litres of water poured over it, the fluid allowed 

 to stand in a cool room for some time, and squeezed out 

 after boiling. To the filtrate so obtained are added 25 

 grm. peptone, 90 grm. sugar, 18 grm. common salt, 9 grm. 

 sodium phosphate, 9 grm. ammonium sulphate, and 25 

 grm. sodium sulphate, and as soon as these ingredients 

 are all dissolved a further addition of 10 to 15 per cent, 

 of gelatine or 2 per cent, of agar-agar is made, and the 

 whole is boiled with continual stirring. After the mass 

 has cooled, but before it has become viscous, the whites of 

 five hen's eggs are mixed in and divided up in the fluid, 

 and when it has been boiled once more until all the 

 albumen is coagulated, 8 to 10 per cent, of glycerine is 

 added. This culture-medium is, when clear, of a straw- 

 yellow colour. It is distributed into test-tubes with a 

 pipette, and sterilised in the steam apparatus for ten 

 minutes on three days in succession. Kowalski has de- 

 scribed very favourable results obtained with it. 



The method given by Heller for the preparation of 

 urine gelatine can also be used to produce urine agar ; the 

 process already given is followed, 1 to 2 per cent, of agar 

 being added instead of the gelatine. 



Gelatine as well as agar media may be prepared with 

 milk or caseine, after the method of Marie Raskin, and 

 peptone can be used as an addition, as also albuminate of 

 soda or potash. 



Miquel has described a nutrient jelly which he pre- 



