AMEBOCYTES WITH SPHERULES. 153 



which the droplets begin to exhibit a basophilic reaction are 

 probably those in which the acid content of the vacuoles has 

 begun to act upon the droplets. Further action of this acid or 

 digestive enzyme renders the cell one in which the droplets, now 

 in the form of larger spherules, are distinctly basophilic in re- 

 action. Thus amebocytes with colorless spherules are inferred to 

 arise from leucocytes which have ingested food. Further evi- 

 dence for this inference is given by the relatively great numbers 

 of amebocytes with basophilic spherules in the intestinal wall 

 in the region of food ingestion. 



It is further possible to conceive that the colorless spherules 

 undergo a gradual digestive change as the amebocyte containing 

 them passes through the tissues of the body. Judging from 

 the sequence of events in intracellular digestion in the Protozoa 

 this change would be in the direction of acid to alkaline. Hence 

 it is inferred that these colorless spherules, during the process of 

 intracellular digestion, gradually give off part of their substance 

 to the tissues through which the amebocyte containing them 

 passes. Subsequently the spherules shrink in size and become 

 alkaline in nature. This change in size and chemical nature 

 could possibly be interpreted as the manner in which red spherules 

 arise. The end product of the red spherules would be the 

 yellows. 



If my inference as to the genetic relationship between the 

 amebocytes with colorless and red spherules is correct then the 

 greater number of amebocytes with red spherules in the peri- 

 visceral fluid is caused by the accumulation here, near several 

 avenues of escape, of degenerating cells. The idea that that the 

 amebocytes with red spherules are degenerating cells is further 

 borne out by observations which have shown that they pass out 

 through the gills, or else they undergo crystalline degeneration in 

 the test (List, '97). 



BIBLIOGRAPHY. 

 Cuenot, L. 



'91 Etudes sur le sang et les glands lymphatiques dans la serie animale. Parti. 



2, Invertebrcs. Arch. Zool., ser. 2, 9, 613-641. 

 Geddes, P. 



'80 Observations sur le fluide perivisceral des oursins. Arch, de Zool. exp. et 

 gener., 8, 483-496. 



