ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 261 



underside of the freezing-plate. The objects, fixed in 10 p.c. formol, 

 are left in running water for two hours to wash out the fixing medium, 

 and then, rinsed with distilled water, are applied to the freezing-plate. 

 Even with a room-temperature of L'l C. blocks of 3 x 10 X 20 mm. 

 will then remain frozen for five minutes. The after-freezing from the 

 chloride-saturated fibrous layer supplies an additional and very welcome 

 protection from the heat produced in working the microtome. Four 

 grammes only of ethyl-chloride were found sufficient to produce the 

 regelation described, and sometimes under favourable circumstances 

 smaller quantities answered the purpose. 



(4) Staining- and Injecting-. 



Staining Spirochseta pallida in Smears with Largine.* — P. 

 Ravaut and A. Ponselle describe their method of staining Spirochseta 

 pallida by means of albuminate of silver. It is well known that the 

 Spirochseta is stainable in sections by the silver method, whilst its 

 demonstration in films is attended with difficulty. The authors have 

 tried various trade preparations of albuminate of silver, but have 

 obtained successful results only with Largine (Lilienfeld). They fix 

 the smear with osmic acid vapour, with a mixture of osmic acid and 

 bichromate, or chromic acid, and also merely with methylic-alcohol. 

 The Largine solution consists of 2-100 grm. of distilled water. It 

 should be fresh and kept in yellow bottles. 



The fixed films are immersed in the Largine solution and incubated 

 at 55° for two hours. Borrel's bottle is used, as it prevents evaporation. 

 The slide is then transferred directly to a bath of 5 p.c. pyrogallic acid 

 for a few minutes : it is advisable to pass the slide into a second bath 

 for cleansing. The slide is then washed in distilled water, after which 

 comes a second bath in Largine for half an hour, and this is followed by 

 pyrogallic acid. It may then be examined. One of the features of this 

 method is that all the microbes are stained. The authors admit that 

 the films lose colour in a few weeks. 



Fat-granules of Bacteria.! — P. Eisenberg describes very fully his 

 experiments on Bacillus anthracis and B. lumesce?is with numerous pig- 

 ments in order to demonstrate the presence of fat-granules. The paper 

 is illustrated by two coloured plates, showing the effect of these dyes on 

 the bacteria. The specimens were drawn under a magnification of 3000 

 diameters. In the bibliography there is no mention of Shattock's 

 demonstration of fat in B. mallei quite ten years ago. 



Demonstrating Bacillus tuberculosis in Cerebrospinal Fluid.J 

 Manicatide draws off 20-80 ecru., or even more, of the fluid by lumbar- 

 puncture into sterilised test tubes, which are left for 6 to 24 hours. 

 The delicate clot which always forms is then fished out with a platinum 

 needle, spread out on a slide, and carefully teased out. The film is then 

 fixed and stained in the usual way. The examination of the slide may 

 be tedious and lengthy, but the results claimed by the author for his 

 method are very satisfactory and definite. 



* C.R. Soc. Biol. Paris, lxv. (1908) pp. 438-40. 



t Centralbl. Bakt,, lte Abt. Orig., xlviii. (1908) pp. 257-74 (2 pis.). 



J C.R. Soc. Biol. Paris, lxv. (1908) pp. 523-5. 



