OUTLINE FOR LABORATORY STUDY OF THE CHICK 349 



The acid alcohol is made as follows: 



Absolute alcohol 70 c.c. 



Distilled water 30 c.c. 



Mix. 



Above solution 99 c.c. 



Hydrochloric acid i c.c. 



Eosin is sold in two forms, that soluble in water and that soluble 

 in alcohol. The eosin soluble in water is preferred, because with it 

 a greater degree of diffusion in stain can be obtained. 



Keep on hand a saturated aqueous solution and dilute with water 

 as needed. The strength of the solution to be used varies somewhat 

 with the tissue and the reagent in which it is to be fixed; but usually 

 the strength should be between J^f o and ^ per cent, when eosin is 

 used after hematoxylin. The diluted solutions should contain 25 

 per cent, of alcohol, otherwise they will not keep well. When eosin 

 is used before an analine dye, such as methylene blue, a 5 per cent, 

 or even a saturated solution should be used. 



To Stain Sections of Liver for the Study of Kupff er Cells. To bring 

 out this reaction Keys suggests the following technic: 



Fix small blocks of the fresh tissue of spleen or liver for 

 eighteen to twenty-four hours in Miiller's fluid plus 5 per cent, 

 mercuric sublimate. Imbed in paraffin and section to 4 microns. 

 Fix sections to slide, and stain twenty to forty minutes with acid 

 carmine. Wash, and transfer to equal parts of a 2 per cent, 

 aqueous solution of potassium ferrocyanid and of a 2 per cent, 

 aqueous solution of hydrochloric acid. Remove after three to ten 

 minutes, wash in distilled water, and pass quickly through a 0.5 

 per cent, aqueous erythrosin solution. Dehydrate in alcohol, clarify 

 in xylol, and mount in Canada balsam. 



To Prepare Anatomical Specimens for a Museum. The 

 Keiserling method gives the best results, since by this method the 

 tissues retain their normal color. The three steps are as follows: 



i. Place the specimen in the following solution and leave from 

 one to seven days, the length of time depending upon the size of the 

 specimen. 



Formalin 200 c.c. 



Potassium acetate 30 grams 



Potassium nitrate 15 grams 



Water. . . . . 1000 c.c. 



