164 Animal Micrology 



Specimens require immersion in a large quantity of the fluid from 

 3 to 10 weeks according to size. The solution should be changed 

 every two days for the first ten days, and later, about once a 

 week. If a scum appears at any time the fluid should be changed. 

 In washing, the tissues are placed in running water for a number 

 of hours and are then treated with gradually increasing strengths 

 of alcohol in the usual manner. For some purposes, however, the 

 tissue is transferred directly from the fluid to 70 per cent, alco- 

 hol. In any event, the material should always be kept in the 

 dark to prevent precipitation. 

 Carney's Acetic Alcohol, see 2. 



9. Chloride and Acetate of Copper (Liquid of Kipart and Petit) . 



Camphor water 75.0 grams 



Crystallized acetic acid 1.0 gram 



Distilled water 75.0 c.c. 



Acetate of copper 0.30 gram 



Chloride of copper 0.39 gram 



This is a good reagent for cytological work where objects are 

 to be studied in as fresh a condition as possible. Methyl green 

 (56) should be used for staining. Only aqueous media are 

 employed with such material. 



10. Chromic Acid. Aqueous solutions of from 0.2 to 1 per 

 cent, are used. The acid is best kept in the form of a 1 per cent, 

 stock solution. Tissues are left in at least fifty times their vol- 

 ume of the acid for from 24 hours for small pieces to one or more 

 weeks for larger ones. The objects are then washed in running 

 water for several hours, after which they are treated with gradu- 

 ally increasing strengths of alcohol. Do the washing and dehy- 

 drating in the dark. If sections of chromic acid material do not 

 stain readily, they should be treated for three hours with acid 

 alcohol, washed out with ordinary alcohol, and then stained. 

 Hematoxylin or some of the anilins are the best stains for chromic 

 material. Chromic acid hardens much more rapidly than 

 bichromate of potash. It makes tissues extremely brittle. 



11. Chromo-Aceto-Osmic Acid (Flemming's solution). 



Chromic acid, 1 per cent, aqueous solution . 15 parts 

 Osmic acid, 2 per cent, aqueous solution . . 4 parts 

 Glacial acetic acid 1 part 



