VITAL STAINING OF AMCEBOCYTE TISSUE. 287 



sequence of amoeboid activity occurs. A second change of acid 

 and alkali has the same effect as the first change. 



This method permits us to observe more completely the effect 

 of the stain on the cells, while in the first method we observed only 

 the later changes. 



We see then that acid and alkali have a very marked effect on 

 the decolorization of the granules previously stained with 

 neutral red and these observations suggested to us the experi- 

 ments reported below' on the decolorization of tissue as a whole in 

 acid, alkaline and neutral media; this latter method makes pos- 

 sible a demonstration of the effect of hydrogen ion concentration 

 on the stained tissue without the aid of the microscope. 



II. In addition to neutral red we tested the effect of some other 

 stains on amoeboid tissue; for this purpose we made use of the 

 first method. We stained the amoeboid tissue in toto and used 

 pieces of the stained tissue in tissue culture experiments. As 

 usual the stains were dissolved in a n/2 solution of NaCl. On the 

 whole our results with the stains other than neutral red were not 

 very satisfactory. 



(a) Methylenblue (1:4000), 2 to 2^2 hours over tissue' in 

 stender dish. Hyaline, as well as granular, cells seem to take on a 

 very slight, diffuse bluish stain; some granules show a more 

 decided bluish coloration. Other cells are hardly stained at all. 

 In some hyaline cells there are some blue droplets, which occasion- 

 ally show a deeper coloration. There is still amoeboid movement 

 noticeable in these cells. 



(6) Methyl violet (i:iooo). In serum less outgrowth than in 

 control; in n/2 NaCl very little outgrowth. Granules stain 

 probably very faintly blue. 



(c) Acriflavine (1:4000). The piece as a whole stains yellow, 

 and the granules also seem to stain yellow. 



(d) Eosin (1:500). The cells are unstained, although the tis- 

 sue as a whole has a pink color. The cells grow out into serum as 

 well as into a n/2 NaCl solution, but much less than in the control 

 of unstained tissue. The injurious effect of eosin seems to be 

 more marked in the sodium chloride solution than in serum; but 

 even in serum some inj ury is noticeable. The cells grow out also 

 into acid and alkaline solutions, but show apparently pathological 

 changes. 



