370 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



agglutination of the colonies in question must be investigated with the 

 specific serum of this disease. 



3. Agglutinin and agglutinating substances are not bodies of con- 

 stant composition and nature ; they appear rather as biological products 

 to differ within certain limits, and this renders desirable the special 

 judging of agglutination results in each case. 



4. The immobilisiug inlthe agglutination of typhoid or coli bacilli, 

 depends on the nature of the specific serum as well as on that of the 

 employed bacteria. 



Capsule Formation by Diplococcus Pneumoniae in Culture.* — 

 M. H. Gordon demonstrates the capsules by the following procedure : 



Fig. 61. 



Boil for 30 minutes, 1 lb. of minced beef in 1 litre of distilled water. 

 Filter and add 12 p.c. of yellow gold table gelatin, 1 p.c. pepton and 

 | p.c. salt. Make faintly alkaline to litmus paper with liquor potassae 

 (B.P.). Add white of egg, and steam for 30 minutes. Filter, pour 

 into tubes, and sterilise in the steamer for 30 minutes on two successive 

 days. 



A drop of the fluid gelatin culture, after incubation at 37°, is re- 

 moved with a loop and spread over a cover-glass, dried over the flame, 

 allowed to stand in alcohol for a minute, and then without drying 

 transferred, film downwards, to a w T atch-glass containing Ziehl-Neelsen's 

 carbol-fuchsin. After staining for 1 to 3 minutes the cover-glass is 

 dipped lightly in water. The moisture is then removed from the upper 

 side, and the preparation is then examined in water. 



Permanent specimens showing the capsules are difficult to obtain by 



* Brit. Med. Journ. (1904) i. p. 659 (1 fig.). 



