The Miceoscopb. 36 



and after leaving it for a night, keeps it in the steam sterilizer at 

 about 212° Fahr. for an hour and a half, stirring occasionally. It 

 is then strained through a felt bag two or three times, when the jelly 

 thus obtained will be found on cooling merely to gelatinize, yet able 

 to withstand a temperature of 87*^ Fahr. before liquefying; but if 

 it is evaporated, it is found to be capable of withstanding a temperature 

 between 122'^ and 131*^ Fahr. before liquefying. In this state, if a 

 test-tube be filled with it, it is found to pi'esent the appearance of 

 water with only a slight degree of haziness. In order to render this 

 more nutritious, and so better fitted for the requirements of the 

 growth of the generality of micro-organisms, the materials recom- 

 mended by Dr. Klein may be added, namely, beef peptone and ordi- 

 nary cane sugar. Add to the jelly 2 per cent, of the former and 1 per 

 cent, of the latter, and the result is a jelly almost as bright as nutrient 

 gelatine and infinitely more so than agar, while the simple method 

 of preparation and the price have much to recommend it. — English 

 Mechanic. 



Watney's Double Stain with Hematoxylin. — Dr. W. Kraus 

 recently reproduced a procedure introduced by Watney for double 

 staining by the exclusive use of haematoxylin. This is effected by 

 successive staining with a strong red and a weak blue solution. The 

 difference between the two solutions really depends upon the quan- 

 tity and acidity of the alum. An intense blue is obtained by the 

 use of freshly prepared dry alum ; the red color appears when acid 

 has become free in the alum, but best when the quantity of the 

 alum solution is less than three times the quantity of the wood-ex- 

 tract. Connective tissue, the protoplasm of the connective-tissue 

 corpuscles, and the walls of vessels are stained red. Mucus, almost 

 all nuclei, and lymjDh corpuscles, are stained bhie. A communica- 

 tion from Prof. Langhaas to Dr. M. Flesch shows that this double 

 stain takes place more simply if Delafield's hematoxylin be used in 

 the ordinary way, and the preparations when mounted in Canada 

 balsam are exposed to the light for a long time. Preparations 

 mounted in glycerin are said to undergo this change. — Journal R. 

 M. Society. 



Pkepakation of Nerves for Microscopic Examination. — To pre- 

 pare a nerve : Dissect out a piece of the sciatic of an ox, horse, dog 

 or cat; the piece should be an inch long and gently stretched upon 

 a piece of wood or a match, and tied at both ends to prevent shrink- 



