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prcparatioiie for Ibiob ipowcre. 



By J. W. GiFFORD. 



WITHIN the last few years, and especially since the Abbe- 

 Schott glass has come into requisition for the construc- 

 tion of lenses, the optical capabilities of the microscope 

 have been so much increased as to make microscopical research 

 rather a question of methods for the more careful and exact pre- 

 paration of the objects to be examined than of further advance 

 from an optical point of view. 



Dr. Lionel Beale was, I believe, the first to point out tliat by 

 the ordinary method of fixing in spirit, staining, and mounting in 

 balsam, many points of minute structure are lost. His glycerine 

 carmine fluid for fixing and staining tissues at once has become 

 classic, and was composed as foUuws : — 



Carmine ... ... lo grains. 



Liquor ammonice ... ... o^ drachm. 



Strong Glycerine ... ... 2 ounces. 



Distilled Water ... ... 2 



Alcohol .. ... oi ounce. 



The carmine is dissolved in the ammonia by heat in a test- 

 tube, and then allowed to stand until the excess of ammonia has 

 escaped. The other ingredients are then added, and the whole 

 filtered. Perfectly fresh material is immersed in this for a period 

 of time varying from six to twenty-four hours, according to size 

 and temperature. The material is then washed in glycerine and 

 water, and placed in glycerine acidulated by acetic acid (ten drops 

 to the ounce) for several days. It may then be cut with \'alcn- 

 tin's knife, or teased out, and mounted in glycerine, with a trace 

 of acetic acid. 



All things considered, there is no doubt that as a general 

 method this still stands second to none, especially where tissues, 

 such as a piece of mesentery or a minute ganglion, do not require 

 to l;e cut into sections, Init may be mounted as they are or teased 

 out with needles. But sections cut with Valentin's knife are 

 scarcely suitable for examination with high powers, and in order 



