768 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



at 37° C. After 10-12 hours the B. icteroicles will be seen to have 

 settled in the lower part of the tube, in fiocculent agglutinated masses. 

 The culture is then cooled down and the gelatin allowed to set. The 

 pointed end of the tube is then broken off, and some of the flocculi 

 removed with a platinum needle, isolation being effected by this means. 

 If the culture is mixed with organisms which naturally fall in masses to 

 the bottom of the culture medium, e.g. streptococci and the proteus 

 varieties, then, the pointed end of the tube having been broken off, its 

 contents are poured in a very thin layer into a Petri dish, and the 

 masses picked out by means of then.' characteristic appearance under the 

 microscope. 



Tubes for the Preparation of Aerobic and Anaerobic Cultures 

 under the Influence of Coloured Rays.* — E. Bartarelli. The apparatus 

 (fig. 170) is made of two large test-tubes. One, measuring 

 25 cm. in length and 3" 5 cm. in diameter, has a small 

 cylindrical tube blown in its lower end. The other, about 

 1 cm. shorter than the first and 2 • 8 cm. in diameter, has 

 near its lower end three indentations. The lesser is placed 

 inside the larger and their edges fused together. The 

 space between the two tubes is now filled with a coloured 

 solution through the hole in the outer, which is then corked. 

 A monochromatic chamber is then produced in the inner 

 tube. In this chamber the culture tube is placed. If 

 anaerobic conditions are required the inner tube may be 

 used a la Buchner. 



Rapid Method of Hardening and Imbedding Tissues.! 

 B. M. Bolton and D. L. Harris found that tissues can be 

 readily hardened and imbedded for cutting into sections in 

 a hot solution of agar and formalin. Nine parts of a 5 p.c. 

 aqueous solution of agar are mixed with 1 part of formalin. 

 The agar is boiled, for several hours, and after the addi- 

 tion of the formalin allowed to clear by sedimentation. 

 The bits of tissue are placed in a wide test tube contain- 

 ing some previously melted mixture. This is kept at 

 60°-70° C. for an hour or longer, and the tissue then 

 blocked, after which it is immersed in strong or abso- 

 lute alcohol for an hour or so, when it is ready to be 

 cut. The whole process does not exceed 3 to 4 hours, 

 when the pieces are not more than 1 cm. in diameter. 



Preparation of Diatoms.} — F. J. Keeley calls attention to the fol- 

 lowing method for studying the structure of diatoms. This consists 

 in depositing on the diatoms a thin film of silver, using the solution 

 ordinarily employed for silvering mirrors, which, dropped on the cover 

 glass containing the diatoms, will silver the latter to a considerable 

 extent before any appreciable quantity of the metal is deposited on the 



* Centralbl. Bakt., 2 te Abt, x. No. 22-3 (1903) pp. 739-40. 



t Journ. App. Micr., vi. (1903) p. 2414. 



% Proc. Anier. Nat. Sci. Philadelphia, lv. (1903) pp. 2-3. 



Fig. 170. 



