1884.] 



MICEOSCOPICAL JOUENAL. 



203 



however, soon tell one when the de- 

 sired point is reached. From the 

 cyanide solution the sections are 

 washed out in water and mounted 

 in balsam in the ordinary manner. 

 The nerve fibres in both the white 

 and grey matter will have a dark pur- 

 ple color, the nerve cells a bronze 

 tint, and the connective tissue a bril- 

 liant saffron tone. 



Any one using these methods for 

 the first time will be struck with the 

 richness of the net-work of nerve fibres 

 in the gi"ey matter of the cord. What 

 was formerly spoken of as gelatinous 

 substance or neuroglia will be found 

 to be mostly nerve fibres. As said, 

 they are not visible under ordinary 

 circumstances, because the intermedi- 

 ate substance stains as intensely as 

 the axis cylinders. At first sight it 

 will appear that the axis cylinders 

 are stained, but closer inspection with 

 high powers will show that these are 

 really unstained, and the white sub- 

 stance of Schwann has taken on the 

 color. In the middle of the bright 

 red or purple spots which represent 

 the cross sections of nerve fibres the 

 unstained axis cylinder can be seen. 

 It is in all respects just the opposite 

 to the ordinary staining of carmine 

 and hfematoxylin. 



These methods are invaluable in 

 the pathology of the cord in tracing 

 degenerated nerve tracts. The de- 

 generated fibres are unstained in the 

 fuchsin and stained yellow with the 

 hEematoxylin, and they offer a strik- 

 ing contrast to the other parts of the 

 cord. Ho\vever, for staining the cord 

 or brain to show lesions other than 

 those of the nerve fibres, I havx found 

 the best results can be obtained with 

 picro-carmine. This can either be 

 made in the manner recommended by 

 Weigert ( Virch. Arch. B'd. 84) or 

 after the formula of Ranvier. It is 

 always a matter of great difficulty to 

 procure a picro-carmine which stains 

 well, and its making seems to depend 

 quite as much on chance as skill. It 

 should always be kept a long time 

 after being: made before it is used. I 



have frequently found that an old for- 

 gotten solution covered with mould 

 would stain in the most brilliant man- 

 ner, while a fresh solution carefully 

 made would give but imperfect re- 

 sults. The sections should remain 

 in the carmine 24 hours, and then be 

 washed out in water which contains 

 a slight percentage of picric acid. 

 Whatever be the method used, it is 

 essential to have fresh tissue to begin 

 with. 



New Microscope Lamps. 



Through the courtesy of Messrs. 

 Walmsley & Co. we are enabled to 

 present this month an illusti'ation of 

 Messrs. Beck's new 'complete' 

 lamp, for use with the mici'oscope. 

 There are no"w in the market a lamp 

 known as the Nelson-Mayall, an im- 

 provement on the original form of the 

 Nelson lamp, which may be regarded 

 as the predecessor of the later ones ; 

 the Beck lamp, and one which has not 

 previously been described, devised by 

 Mr. Bulloch. 



The value of these lamps will not 

 be immediately appreciated, except by 

 those who have had experience in the 

 refinements of manipulation vv^ith the 

 microscope. For fine work and del- 

 icate management of the light, either 

 for purposes of observation or display, 

 they are very useful. Although not 

 indispensible to the working mici'o- 

 scopist, they are certainly a great con- 

 venience, and those who can afford 

 to purchase the best apparatus should 

 not neglect to add a good lamp to 

 their collection. It is true, one can 

 do anything with a common hand- 

 lamp and a good bull's-eye conden- 

 ser that can be done with these lamps, 

 but at no little sacrifice of time and 

 patience. Those who are accus- 

 tomed to regarding a student's or an 

 an ordinary hand-lamp as quite suf- 

 ficient for all purposes, will be un- 

 able to understand the superiority of 

 these more elaborate and expensive 

 devices. We shall endeavor to ex- 

 plain their advantages in a few words. 



