200 PRACTICAL MICROSCOPY. 



SILVER STAINING SOLUTION. 



Nitrate of Silver, 5 grains. 



Water (distilled), 4 ounces. 



Used for the demonstration of cement substance between cell elements. 



OSMIC ACID SOLUTION. 



Osmic Acid, 1 gramme. 



Water, 100 cubic cent. 



The acid is found in market sealed in glass tubes holding one 

 gramme each. The utmost care should be taken to avoid inhaling 

 the vapor from the pure acid as it produces an intense inflammation 

 of the respiratory surfaces. The best method of handling the 

 material is to measure 100 c.c. of water, place it in a strong bottle, 

 and then drop in the tube containing the osmic acid. Then with a 

 glass rod break the tube. The bits of glass need not be removed. 

 Keep the bottle, tightly stoppered, in a cool dark place. 



Osmic acid is used in histology on account of its action upon fatty 

 substances, i. e., staining them of a deep brown or black. 



WEIGERT'S H^EMATOXYLIN STAINING FOR MEDUL- 

 LATED NERVE TISSUE. 



Formula. 



1. A saturated aqueous solution of neutral acetate of copper. 



2. Strong haematoxylin staining fluid, vide text. 



3. Borax, ferridcyanide of potassium, aa 1 drachm. 

 Water 4 fluidounces. 



Process. 



1. Allow the sections to remain in 1 for twenty-four hours.* 



2. Wash in clean water for a few moments only, and transfer to 2. 

 Brain sections will require from two to three days, and spinal cord 

 twenty-four hours for complete staining. They must appear almost 

 black. If the hardening has been effected with the bichromate solu- 

 tion as given in the text (vide hardening fluids), maceration of the 

 sections in the cupric acetate may be omitted. 



3. Wash in water for five minutes and transfer to 3. They may be 



* The haema. solution gives the best results, in this staining, if kept at tem- 

 perature of about 100 F. 



