J, W. GROVES ON SECTIONS OF ANIMAL TISSUES. 241 



The borax carmine is thus prepared : — 



1. Carmine, 3 \. 



2. Borax, 3 2. 



3. Distilled Water, | 4. 



Place 1 and 2 dry in a mortar, and mix ; then dissolve in warm 

 water for 24 hours ; after which pour off the supernatant fluid, and 

 the solution is ready for use. 



The acid carmine fluid of Schweiggerseidel is also useful in some 

 cases, though Schafer's acid logwood, already noticed, is preferable. 



So far we have had to do only with stains that change but little 

 if at all. Those which we now come to, however, do change 

 materially— ?'.£., get rapidly darker and more opaque, till they reach 

 a stage when they are utterly useless. They differ from all the 

 others, with the exception of molybdate of ammonia, in the fact that 

 the action of light is necessary to produce the colour. 



Nitrate of silver, which was introduced by Recklinghausen, is 

 used in a half per cent, aqueous solution. Specimens to be acted 

 upon should be dipped in distilled water to remove any trace of 

 sodium chloride, and then steeped in the silver solution for some 

 two or three minutes, after which they should be washed in ordinary 

 water till it ceases to turn milky ; then placed in glycerine and 

 exposed to the action of light, until they assume a dark brown 

 colour, when they may be mounted in glycerine or glycerine jelly. 



By means of this stain the endothelial cells of the lymphatics, 

 blood-vessels, &c, and the nodes of Ranvier in medullated nerves, 

 are rendered evident. They may subsequently be stained with log- 

 wood, carmine, or chloride of gold. 



Many methods have been adopted for staining with gold chloride. 

 I will mention three — Dr. Klein's, Dr. C. Bastian's, and Mr. 

 Schafer's. 



1. Dr. Klein's method for showing the nerves in the cornea is as 

 follows : — Remove the cornea within 15 minutes of death ; place it 

 in a half per cent, chloride of gold solution for half an hour to a hour 

 and a half or more ; wash in distilled water, and expose to the 

 light for a few days, the water being occasionally changed. Then 

 place in glycerine and distilled water, in the proportion of one to 

 two ; subsequently place it in water and brush gently with a 

 sable pencil to remove any precipitate, when it may be mounted in 

 glycerine. The cornea should now be of a grey violet tint. 



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