VITAL STAIXIXG OF AMCEBOCYTE TISSUE. 289 



Eosin Tissue. Within a few minutes eosin tissue gives off stain 

 readily to the alkaline (w/iooo NaOH) solution, a small quantity 

 of stain to the neutral (n/2 NaCl) solution and none to the acid 

 (w/iooo HC1) solution. This is in accordance with the acid 

 character of the staining radicle in eosin. Eosin differs from 

 neutral red not only in the reversal of the action of acid and 

 alkali, but also in the greater ease with which a neutral sodium 

 chloride solution causes the movement of the stain from the 

 tissue to the solution. 



Amcebocyte tissue stained with other stains gives less definite 

 results. Methylviolet is apparently extracted equally by all 

 solutions. Trypanblue does not give off enough stain to make 

 comparisons possible. Acriflavine (1:4000) stains amcebocyte 

 tissue deep yellow; alkaline, acid and neutral solutions seem to 

 extract the stain equally well. Nileblue, on the other hand, 

 bahaves somewhat similarly to neutral red. Acid (w/iooo HC1 

 in n/2 NaCl) extracts the greatest amount of this stain, n/2 NaCl 

 extracts a small amount, but alkali (w/iooo NaOH in n/2 NaCl) 

 extracts none. 



We see then that there is a definite relation between the acid or 

 alkaline character of the dye used, and the character of the 

 solution, which is most effective in extracting the stain from the 

 stained tissue. It is not possible to modify this result if, previous 

 to staining the tissue, we treat it on the following manner: we 

 first allo\v acid (w/iooo HC1) or alkali (w/iooo NaOH) in isotonic 

 n/2 NaCl solution to act on amcebocyte tissue for a period of 

 three hours. The tissue is then washed with n/2 NaCl until the 

 washings are neutral to brom thymol blue, when it is stained 

 with neutral red (i :2OOo) for two hours, and then again washed 

 until the wash fluid becomes colorless. After such preliminary 

 treatment we found that the tissue previously exposed to alkali 

 stained much lighter with neutral red than tissue exposed to acid 

 or control tissue. Against acid, alkaline and neutral solutions 

 the acid and alkali tissue behaved similarly. 



If such acid or alkaline tissue is stained with eosin instead of 

 with neutral red, the tissue behaves exactly like ordinary eosin 

 tissue: the eosin is extracted by alkali, slightly by a neutral 

 solution and not at all by acid. 



