MICROSCOPICAL TECHNIQUE. 395 



Nutrient Gelatine.— To prepare this, first make beef broth by 

 mincing 450 gm. of lean beef, free from all fat and connective 

 tissue, and boiling for half-an-hour in a large flask, with a litre of 

 distilled water. Filter and make up to one litre with water, then 

 add sodium chloride 5 gm. and pure peptone 10 gm. Heat the 

 mixture in a flask on a water-bath at 100" C. for an hour, shaking 

 from time to time. Now cautiously add concentrated solution of 

 sodium carbonate until faintly alkaline, and again heat at 100^ C 

 for half-an-hour. Next, allow 100 to 120 gm. of sheet gelatine to 

 soak in the broth for half-an-hour ; heat slowly on a water-bath 

 until the gelatine is dissolved ; neutralise carefully, and again heat 

 for half-an-hour. Then add the white of an egg, heat till all the 

 albumin is precipitated, and finally filter through two layers of 

 moist filter-paper, on a hot-water funnel, into sterilised flasks, and 

 sterilise on a steam steriliser for twenty minutes on each of two 

 successive days. — Pharmaceutical Journal. 



Inoculating Culture Tubes.*— Beneke recommends that gelatin 

 culture tubes should be inoculated by making a puncture at the 

 side of the medium close to the glass. The advantage of this 

 method over the older plan of inoculating the mass in the middle 

 is that the growing culture can be microscopically examined from 

 the outside and various details made out, such as the nature of 

 the growth, the comparative appearance of colonies near the 

 surface and those situated more deeply, and the presence of one 

 or more distinct organisms. If the tubes used have the opposite 

 sides flat and parallel, such examinations will be still further 

 facilitated. 



A New Method of Preparing Serum Agar-Agar.— Drs. Kant- 

 hack and Stephens suggest in the Lancet the utilisation of patho- 

 logical serum, such as ascitic, pleuritic, and hydrocele fluids, of 

 which there is always a large supply at a hospital, for the prepara- 

 tion of serum agar-agar culture medium for the separation of the 

 typical diphtheria bacilli. The following method gives a beautifully 

 clear and transparent medium in less than half-an-hour: — To every 

 100 c.c. of serous exudation, 2 c.c. of 10 per cent, caustic potash 

 is added ; i '5 to 2 per cent, of agar-agar previously soaked in 



*Cent,f. Baki. in Pharm. Journ. 



