PHAGOCYTOSIS IN PERIVESICAL FLUID OF ARBACIA. 15! 



further history of the relation of the clot to the tissues originally 

 occupying the resected area -will be followed later. 



SUMMARY. 



1. Phagocytosis in the perivisceral fluid of Arbacia is carried 

 on by the leucocytes alone. These cells possess membranous 

 processes similar to those of the leucocytes of Asterias and are 

 the smallest and most numerous of the amibocytes. As phago- 

 cytes the leucocytes have a long period of activity. 



2. The leucocytes tend to agglutinate even in freshly drawn 

 perivisceral fluid. In a drop of perivisceral fluid on a plane 

 surface, the leucocytes lose their characteristic membranous 

 processes upon contact with the surface and become elongate. 

 Long filamentous processes are produced by the shrinkage of 

 the membranous processes. These filamentous processes adhere 

 to those of neighboring leucocytes forming a delicate mesh to 

 which the pigmented and colorless amibocytes adhere. 



3. The leucocytes show an alkaline reaction when treated 

 with neutral red in sea-water, but are not affected by weak 

 solutions of intravitam stains introduced into the perivisceral 

 cavity. 



4. If a piece of the peristomial membrane or the test is resected, 

 the leucocytes form a clot which closes the wound. 



BIBLIOGRAPHY. 

 Cuenot, L. 



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Partie 2. Invertebres. Arch. Zool., Ser. 2, Tome 9: 613-641. 

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'01 Ueber die Trombocyten (Blutplattchen). Anat. Anz., 19: 529-540. 

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