RELATION OF BURSARIA TO FOOD 37 



It is evident that the solution of janus green drawn from the 

 mixed suspension, and produced by the Hberation of the stain 

 from the stained yolk grains of the mixture which was not eaten, 

 did not now prevent the animals from eating unstained yolk 

 grains which were placed in it; hence it was not the stain in 

 solution which prevented the eating of the stained grains of the 

 mixture from which the solution was drawn; but the stain which 

 was adsorbed by the yolk grains of the mixture and diffused 

 from them. Many such similar tests were carried out giving 

 the same result. This does not mean that the solution apart 

 from theT yolk grain with its adsorbed dye, may not affect the 

 result of the feeding, for in higher concentrations the solution 

 apart from the stain upon the grain does affect the feeding proc- 

 ess. In solutions of lower concentrations of the appropriate dye 

 the chemical nature of the grain along with the amount of dye 

 adsorbed, are the essential factors determining the number of 

 grains which will be eaten. 



c. Hematoxylin. To show further that the specificity of the 

 toxic agent plays a large part in determining whether or not yolk 

 will be eaten, the following experiments are given. It will be 

 noted that in this case we have a substance which has a very 

 different effect upon the cell and its relation to food, from that 

 produced by the substances thus far dealt with. The solution 

 in this case may be made very deep brown while the grains are 

 also stained deeply, and yet the yolk grains are eaten even in 

 solutions which kill the animals if they remain in it more than 

 three or four minutes. 



Experiment XX: Table 22 (a) and (6). The same quantity of yolk 

 was added to each of nine dishes of 8 cc. capacity, each containing 

 equal amounts of tap water. The dishes were numbered 1, 2, 3, and 

 so forth. To these were added diverse quantities of the 0.5 per cent 

 aqueous solution of hematoxylin by drops, as given in the tables; time 

 of feeding ten minutes. 



This experiment was repeated with the same suspensions at 

 the end of one hour; time of feeding fifteen minutes (table 22 6). 

 The individuals which died before the count was made are de- 

 noted by X. The tables show that although the solutions, espe- 



