152 THE MICROSCOPE. 



M>tUi:X\mxs, 



Microscopy. — Dr. Bermann, in the Archives of Medicine gives 

 "Some Points on Staining in Toto and Dry Section Cutting," which 

 are of so much practical use, that I shall give them for the benefit 

 of those, who may be interested in the subject, or as the doctor says: 

 "For the benefit of those medical men, who wish to consider the 

 study of pathological microscopy, as it enables them to work when- 

 ever they find leisure and to leave off at any stage of the proceed- 

 ings, without fear of spoiling what is unfinished." For hardening 

 tlie tissues, with scarcely an exception, MuUer's fluid (containing 2^ 

 parts of bichromate of potash, i to \\ parts sulphate of soda and 100 

 parts distilled water) is to be preferred, because it hardens the 

 tissues without shrinkage, and almost preserves their natural appear- 

 ance. It may not be amiss here to mention that it can be satis- 

 factorily employed only when the following rules are strictly ob- 

 served: 



1. The greater the quantity of fluid, within certain proportions 

 to the size of the specimen to be hardened, the more confidently one 

 may count upon its success. 



2. The fresher the specimen, the more accurate and reliable 

 will be the definition of the cellular construction of the 

 sections — specimens not prepared after this fashion will under 

 no circumstances repay the labor and trouble expended upoa 

 them. 



Besides slightly staining the tissue, MuUer's fluid has the advan- 

 tage of preserving the blood corpuscles in the vessels better than 

 other hardening agents, but to attain this end the fluid, which is 

 perfectly transparent, should not be allowed to lose its transparency 

 and must be very frequently changed — not less than twice on the 

 first day, and then (according to the quantity of the fluid) at least 

 every other day. A small piece — say half a cubic inch — requires 

 about a week to attain the right consistency, when, after first wash- 

 ing it in water, it is transferred into alcohol of about 75 per cent. 

 It is not absolutely necessary to harden the specimen, in MuUer's 

 fluid first; those put only in alcohol in the beginning will stain just 

 as well. I prefer to use MuUer's fluid, because most tissues shrink 



