VITAL STAINING OF AMCEBOCYTE TISSUE. 285 



assumed the neutral red stain, entering a pseudopod. In a 

 similar way in cells which had grown out into a n/3 solution of 

 KC1, and in which circus movements developed in the amcebo- 

 cytes, one or more stained granules participated in this circus 

 movement in some cases. Even the droplets stained with 

 neutral red seemed occasionally to enter a pseudopod. 



Not only the cells which had grown out into Limulus serum and 

 into neutral solutions of sodium chloride contained these droplets 

 or particles of neutral red, but even cells which had grown out 

 into acid (n/iooo HC1) and alkaline (n/2OO NaOH) solutions of 

 sodium chloride showed the typical neutral red droplets. 



We have reason for assuming that originally the neutral red 

 entering the cells stained the cell granules and that it was only 

 secondarily deposited in droplets in the amcebocytes. The 

 granule stain evidently had to a great extent disappeared at the 

 time when the slides were examined. However, subsequently 

 even the droplets, especially in the periphery of the field of 

 outgrowth, disappeared in a number of cells in the course of 

 several days. It seemed as if the droplets dispersed gradually 

 into very fine particles and thus were ultimately destroyed. 

 While, as we stated, the cells, as far as their staining with neutral 

 red is concerned, did not at the time of examination show any 

 difference in acid, alkaline and neutral solution, it is possible that 

 later the droplets of neutral red disappeared somewhat more 

 rapidly in the acid than in the alkaline solution; this, however, 

 needs further examination. 



However, in many cases the droplets remained unchanged even 

 after the cells had been destroyed and the distribution of these 

 neutral red droplets or particles indicated where cells had been 

 previously. 



We made use of this method of staining pieces of amcebocyte 

 tissue with neutral red, in order to study the behavior of cells 

 coming simultaneously from two different pieces of amcebocyte 

 tissue and moving towards each other. For this purpose we 

 placed two pieces, one stained and the other unstained, side by 

 side on a cover glass. Where the two pieces came nearest to 

 each other, the zone of outgrowing cells from both joined and 

 formed a bridge connecting both pieces. 



On the whole the tissues derived from the red and from the 



