RELATION OF BURSARIA TO FOOD 



45 



Fig. 4 Experiment XXIV. Curve A represents the course of total extrusion 

 of Sudan III; curve B, that of complete digestion of cold-ether extracted yolk; 

 curve C, course of complete disappearance of fresh fat-containing yolk. 



course of the extrusion of Sudan III or of the disappearance of the 

 yolk from the cytoplasm, but it will be noted that the great difference 

 appears in the observation at the end of seven hours. At the end of 

 twenty-two hours A had no traces of Sudan III, B still had six and 

 C had ten individuals with food. 



This early extrusion of indigestible substances is considered 

 in more detail in connection with Chinese ink in the following. ^^ 



Experiment XXV. Two sets of fortj^-eight individuals each were 

 fed, one with cold-ether-extracted 3^olk, the other -wdth Chinese ink. 

 Examination of the cell content was made at hour intervals as indicated 

 by numbers on the basal abscissa. Ordinates indicate the number of 

 individuals which had extruded all the ink content in the time indi- 

 cated (curve A). In curve B the ordinates represent the number of 

 individuals fed extracted yolk in which yolk had disappeared at the 

 end of the time indicated by the abscissa. Chinese ink in suspension 

 is much more readily eaten than carbon or aluminium and is therefore 

 more convenient. This is to be explained by the fact that there are 

 present mucilaginous soluble substances in the Chinese ink which serve 

 as agents inducing a more positive feeding reaction and are possibly 

 of some slight food value. The ink was not found to be injurious to 

 the animals. The greater part of the ink is thrown out quite early 

 while slight traces may remain for some time longer. The time dur- 

 ing which the ink was retained was taken to end when the last trace 



^1 In order to obtain satisfactory results with such substances as Sudan III 

 and aluminium in aqueous suspension the adsorbed gases should be driven off 

 before feeding. 



