76 Animal Microloyy 



Teasing. -In teasing the important thing to remember is that the 

 elements of the tissue are to be separated, not broken up. Both patience 

 and sharp clean needles are indispensable. The process is best carried 

 on under the lens of a dissecting microscope, although it may be done 

 without such aid. A background which enables the tissue to be seen 

 distinctly should be selected, black for colorless or white for colored 

 objects. Black-and-white porcelain slabs are made for this purpose and 

 are very convenient. A good dissecting microscope has attached beneath 

 the stage a reversible plate one side of which is black, the other white. 

 Use a small piece of tissue and begin teasing at one end of it. 



2. With the aid of a dissecting microscope carefully tease out 

 in water a number of fibers. Use a small piece and, beginning 

 at one end, with both needles separate the piece along its entire 

 length into two; likewise further subdivide these until the ulti- 

 mate fibers are isolated. 



3. Transfer some of the fibers through the alcohols and xylol 

 and mount in balsam. Stain others in picro-carmine for 5 to 10 

 minutes and mount in glycerin as above. 



C. Maceration by Means of Hertwig's Fluid (Hydra. Testis). 

 1. The solution consists of: 



0.05 per cent, aqueous solution of osmic acid . 1 part 

 0.2 per cent, acetic acid 1 part 



Prepare the ingredients for this mixture by diluting the stock 

 solution (1 per cent.) in each case with distilled water. Make a 

 separate 0.1 per cent, solution of acetic acid also. 



2. Treat a hydra with the osmic and acetic acid mixture for 

 3 minutes and then transfer it to the 0.1 per cent, solution of 

 acetic acid. Wash in several changes of this fluid to remove all 

 osmic acid and let the hydra remain in the acetic acid for 12 hours. 



3. Wash in water, stain in carmalum (reagent 34, Appendix 

 B) or better in Acid carmine (reagent 37), and mount in glycer- 

 in as above. If the cells are not sufficiently separated, gently 

 tap on the cover glass. 



4. Submit small bits of the testis of some animal to the same 

 treatment. Stain with methyl green (reagent 56) or acid car- 

 mine (reagent 37). 



