05G SUMMARY OF CORRENT RESEARCHES RELATING TO 



closed at its lower end by a layer of cotton -wool 5 cm. thick ; the fluid 

 is then poured in and the upper end closed with a caoutchouc plug, in 

 which is an opening for a glass tube. To the glass tube is connected a 

 rubber bellows which, when worked, compresses the air inside the tube, 

 so that the agar soon rims out quite clear, and is then sterilized in the 

 usual manner. 



(2) For preparing gelatin, 1^ litre of water, 22*5 gr. (1^ per cent.) 

 Kemmerich's meat-peptouo, and 45 gr. (3 per cent.) peptone, are boiled for 

 some minutes in a metal pan over tlie open fire and then cooled dowTi to 

 50-60^ C. In this mass are dissolved 225 gv. (15 per cent.) gelatin, 

 and the solution neutralized with carbonate of soda. The whole mass 

 is then shaken with the white of an egg and steamed for 1/2 hour ; 

 the albumen and other substances are precipitated, and then filtration 

 is done in the way described above. The water-clear gelatin is then 

 distributed into flasks and sterilized in the usual manner. 



(3) For i^rejiaring a fucus mass, the same directions as were given 

 for agar must be followed, except that 2^ per cent, Fucus crispus is 

 used. Before neutralization it must be strained through a cloth, as 

 Fticua crispus is not so perfectly soluble as agar. 



Preparing Agar-agar.* — Dr. E. Freudcnrcich prepares agar, and at 

 the same time shortens the process in the following manner: — 1 per 

 cent, of agar is added to meat infusion, and the mixture boiled on the 

 open fire until the agar is quite dissolved. The solution is then neu- 

 tralized and afterwards reboiled until the albuminous matters are preci- 

 pitated. So much of the solution as will be required to fill a flask or 

 test-tube is then poured into a funnel with jDaper filter and placed in a 

 steam sterilizer, and the temperature raised to about 110^, and in about 

 one hour the glass vessel will have received its proper quantity of clear 

 agar. Of course, several flasks, &c., may be got ready at the same time. 

 When complete the vessels are plugged with cotton-wool, and in this 

 way one sterilization is saved. 



Milk-peptone-gelatin for cultivating Pathogenic Micro-organisms.t 

 — Mdlle. M. Easkin prepares milk-poptone-gelatin by warming 1000 ccm. 

 of new milk to 60°-70" C, and then adding 60-70 gr. of solid gelatin. 

 When the gelatin is dissolved the solution is boiled until complete 

 coagulation of the casein has taken place. It is then strained through a 

 linen cloth into a wide glass vessel, in order that the fat may ascend to the 

 surface without difficulty, and when it has settled the fat is skimmed off. 

 When freed from the fat the mixture is heated and 1 per cent, peptone 

 added, and then soda to neutralization. The addition of NaCl increases 

 the nutritive value of the quite clear transparent gelatin. 



The preparation of milk-peptone-agar is somewhat more complicated. 

 To 1000 ccm. of milk are added 50 ccm. gelatin and five to seven pieces 

 of agar cut up small. After standing for fourteen hours at the ordinary 

 room temperature, the mixture is boiled for three hours until the casein 

 is coagulated ; the rest of the procedure is as in the foregoing 

 preparation. 



In preparing milk-casein-gelatin and milk-casein-agar, 150 ccm. of 



* Centralbl. f. Bakteriol. u. Parasitenk., iii. (1888) pp. 797-8. 

 t Petersburger Med. WochenscLrift, 1887, pp. 20-43. Cf. Centralbl. f. Bactcriol. 

 u. Parasitenk., iii. (1888) pp. 5G8-9, 



