STAINING ANIMAL TISSUES. 225 



nervous textures, like the retina, may be permeated by 

 the strongest glycerine, and, when fully saturated with it, 

 dissected with a /degree of minuteness unattainable in any 

 other way. " The smallest animalcules, entozoa, polyps, 

 molluscs, insects, Crustacea, fungi, algae, and the delicate 

 parts of vegetable tissues, are equally well preserved by 

 it." All the various colouring-solutions, as carmine, aniline, 

 &c., should be always prepared for use with glycerine or 

 syrup as a basis. 



The staining or colouring fluid employed by Dr. Beale 

 is made as follows : Carmine, 10 grains ; strong liquid 

 ammonia, J drachm. ; Price's glycerine, 2 ounces ; dis- 

 tilled water, 2 ounces ; alcohol, |- ounce. The carmine 

 is >to be placed in a test-tube, and the ammonia added to 

 it. Upon applying the gentle heat of a spirit-lamp, it is 

 dissolved. Boil it up for a few seconds, and allow it to 

 cool before adding the glycerine and rest of the ingredients. 

 Lastly, pass it through a filter, or allow it to stand by and 

 decant off the clear solution. The solution should neither 

 be too alkaline, nor perfectly neutral ; if the former, the 

 colouring becomes too intense, and thus much of the soft 

 or imperfectly formed tissue is destroyed; and, if the 

 latter, the uniform staining of tissue and germinal matter 

 equally mars the result. The permeating power of the 

 solution may be increased by the addition of a little more 

 water and alcohol. 



After the specimen has been properly stained, it should 

 be washed in a solution, consisting of strong glycerine two 

 parts, water one part ; and then transferred to the following 

 acid fluid: Strong glycerine, one ounce; strong acetic acid, 

 five drops; where it must remain three or four days to 

 regain the volume it occupied when fresh. To mount 

 specimens so prepared, take a small portion and spread it 

 out on the glass-slide ; add a drop of fresh glycerine, and 

 cover with thin glass ; warm it gently, and press it down, 

 with a needle-point. 



Examine the specimen with a quarter power, and, if a 

 good deal of granular matter appears to be mixed in with 

 it, remove the glass cover, and wash it by adding drop 

 after drop of the glycerine and acid solution. The slide 

 fcliould be inclined, and, at the same time, gently warmed 



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