Irving Hardesty 331 



results and g]3'cerine mounts aro very inconvenient for work with high 

 power objectives. 



After considerable trial, teasing with a lino stream of water was found 

 to give much the best results with the material. The following simple 

 arrangement proved very etlicient: A strip of the fixed tissue was pinned 

 by one end to the middle of a small piece of thin, carefully smoothed 

 wooden board 4 or 5 inches long by 1 inch wide. With the free end of 

 the specimen downward, the board was held in the left hand with its 

 lower end resting at a slight angle upon the bottom of a slender dish of 

 suitable dimensions, while with the right hand a stream of water the 

 size of a fine needle was directed upon the specimen. The bits of dis- 

 sociated tissue wash down into the stender dish, and a wooden board 

 seems to give less spattering and rebounding of the water than a strip of 

 glass, especially a glass slide with a cell or groove in it. A piece of 

 8-millimeter glass tubing drawn out to the required capillary dimensions 

 and broken off squarely and the large end thickened and bound securely 

 into a piece of rubber tubing was used in obtaining the sufficiently fine 

 stream of water. This was securely attached either to the tap direct, 

 and the tap water used, or attached to a Woulfe bottle containing dis- 

 tilled water under pressure, the pressure being obtained by attaching the 

 reverse side of the Woulfe apparatus to an air force pump. 



With sufficient pressure, a strip of tissue is washed down to a shred 

 in a few minutes. The stream is best directed against it with a slight 

 up and down, brushing motion. After two or three strips have been 

 teased, or until the stender dish is nearly full of water, the dish is set 

 aside and another taken if recpiired. The nerve fibers being stained 

 black by the osraic acid, the stender dish is placed upon a white surface. 

 The material soon settles to the bottom of the stender and the water may 

 be practically all withdrawn. Then the material from several stenders 

 may be all transferred to one smaller stender and again allowed to settle. 

 Then more water may be withdrawn and the material counterstained if 

 desired. 



For counterstaining I used 1 per cent aqueous acid fuchsin, which is 

 known to stain osmic material readily and can be easily controlled. It 

 was only desired in the teased preparations to demonstrate the shape 

 and position of the sheath cells. iVfter being in the fuchsin the required 

 time, the material was washed first in 50 jDer cent and then in 70 per 

 cent alcohol. It settles in alcohol more quickly than in water and the 

 alcohol may be drawn off more completely. 



Dehydration was completed with 95 per cent alcohol and finally with 

 two changes of absolute. Tlien the absolute was replaced with a clearing 



