46 METHODS OF CULTIVATION OF BACTERIA. 



Streptococci, but Marmorek has succeeded in doing so by grow- 

 ing them on the following media, which are arranged in the 

 order of their utility : — 



1. Human serum 2 parts, bouillon i part. 



2. Pleuritic or ascitic serum i part, bouillon 2 parts. 



3. Asses' or mules' serum 2 parts, bouillon i part. 



4. Horse serum 2 parts, bouillon i part. 



Human serum can be obtained from the blood shed in 

 venesection, the same precautions being taken as in the case of 

 that got in the slaughter-house. In the case of these media, 

 sterilisation is effected by method B (4), and they are used fluid. 



Hiss's Serum Media. — Their use is for a more efficient 

 means of differentiating pneumococcus from streptococcus pyo- 

 genes, and they bear some resemblance to those of Marmorek. 



A. Ox serum i part. 

 Distilled water 2 parts. 



Normal sodium hydrate o. i per cent. 



B. Ox serum i part. 

 Distilled water 2 parts. 

 Inulin i.O per cent. 



They can be sterilised intermittently at 100° C. without 

 coagulating. In either medium pneumococcus forms acid and 

 coagulates the serum, but more rapidly in the latter, whilst 

 streptococcus does neither. 



Potatoes as Culture Material. 



(a) In Potato Jars. — The jar consists of a round, shallow, 

 glass vessel with a similar cover {vide Fig. 11). It is washed 



with i-iooo corrosive sublimate, and a 

 piece of circular filter paper, moistened 

 with the same, is laid in its bottom. On 

 this latter are placed four sterile watch- 

 glasses. Two firm, healthy, small, 

 round potatoes, as free from eyes as 

 Fig. II. -Potato jar. possible, and with the skin whole, are 



scrubbed well with a brush under the tap 

 and steeped for two or three hours in i-iooo corrosive sublimate. 

 They are steamed in the Koch's steriliser for thirty minutes or 



