50 METHODS OF MICROSCOPICAL RESEARCH. 



tated limb of a crab for a week in absolute alcohol. 

 A bit of muscle is scooped out, stained and mounted, 

 after being teased with needles. Non-striped muscle 

 may be demonstrated thus : Kill a small animal 

 and wash out a length of the , small intestine with 

 salt solution, distend it with absolute alcohol, and 

 tie both ends, then suspend it in the alcohol for 

 twelve hours. With a pair of blunt-pointed forceps 

 now tear off strips from the outer surface, which 

 will include the longitudinal muscle structure ; stain 

 them and mount in balsam. 



Picric Acid. 



Make a cold saturated aqueous solution. Small 

 pieces of tissue harden in this in from twelve to 

 forty-eight hours. It is excellent for decalcifying 

 foetal bones which may be left in it, and tested from 

 time to time with a needle, which ought to be 

 pushed easily through them. No time can be 

 specified, in some cases perhaps weeks may be re- 

 quired. Prepare the varieties of cartilage with this 

 solution. The aorta (pieces) of a large animal 

 (horse, or ox), also a cornea to show its fibrous 

 tissue, the thymus gland of an infant, also a lym- 

 phatic gland may all be well prepared by remaining 

 in this solution twenty-four, thirty-six, or per- 

 haps forty-eight hours. The intracellular plexus 

 of fibrils may be well shown, thus : Keep a newt 

 in a little water for three, four, or five days without 

 changing the water. Its outer layer of cuticular 

 epithelium is shed as a cast of the entire animal. 

 Place the film in the solution for twenty-four hours, 

 then wash in plain water till no colour is given off, 



