THÉEL, THE AMOEBOCYTES BY ECHINODERMS. 23 



form (pl. 7, fig. 5), but some of them are more elongated 

 reaching a length of 10 to 12 \s.. They lodge a number of 

 vacuoles of various dimensions (p. 7, fig. 7), sometimes in 

 such a quantity that the cell gets a reticulate structure (pl. 

 7, fig. 8). On the other hand I have seen blood-cells with a 

 single voluminous vacuole (pl. 7, fig. 6). It ought to be added 

 that I never observed them to give any tinge of red to the 

 coelomic fluid. 



Coagulatioii of the coelomic fluid. 



In my paper on Parechinus miliaris the pages 4 to 9 

 are devoted to some reflections on the coagulation-pheno- 

 mena which occur in the coelomic fluid of that species. Al- 

 ready in 1896^ I called attention to the excellent paper of 

 Geddes^ on the perivisceral fluid of echinids. After a short 

 survey of the coagulation-process of human blood, he says 

 on page 486: »Le phénoméne qu'on remarque ici est tout å 

 fait différent; on ne voit pas de fibrine, mais les corpuscules 

 blancs que nous venons de décrire s'attachent Tun a Tautre, 

 et förment des tas irréguliers ou des masses en for me de mures ». 

 For my part, I adj oined some remarks on the différent ways 

 in which the coagulation takes place in Echinus esculentus, 

 when the coelomic fluid has been emptied into a low, flat 

 glass or in a long, tubular glass. At that time, also I my- 

 self was convinced that the coagulation of echinoderm fluid 

 was due solely »to the presence of innumerable white corpuscles 

 or amoebocytes, which join together into an irregular large- 

 meshed net-work, visible to the naked eye». 



Previously, in 1891, Cuénot^ pronounced the same views 

 on the coagulation-process in the echinids. He wrote as 

 follows: »Cette pseudo-coagulation est tout å fait différent de 

 la coagulation fibrineuse, il est a peine besoin de le faire ré- 

 marquer, la fibrine man que tout a fait chez les Oursins; cette 

 particularité est liée a la longueur et å la mobiUté exceptionelle 

 des pseudopodes des amibocytes». 



Continued studies of the coelomic fluid of Parechinus mi- 



^ Remarks on the activity of ainoeboid cells in the echinoderms. Up- 

 sala 1896. 



•^ Arehives d. Zool. expérimentale. T. 8. Paris 1879 — 1880. 



^ Arehives d. Zool. expérimentale. Sér. II, T. 19. Paris 1891. 



