7 HJALMAR T HEEL: ACTIVITY OF AMOEBOID CELLS 04 THE ECHINI 



made by Cuénot and other investigators with regard to th< leration ol the 



echinoid-skeleton. Thus, for instance, I removed near the apical pole .. p I the 



shell in two large specimens of Echinus esculentus, making a quadrangul ning 



of slightly more than one centimetre. The operation was effectuated und* i 

 and special earc was taken to violate the animals in the least possibl« i Th 



the echini were left in well aerated aquaria with a superfluity of running sea-wi 

 and they seemed vigorous and in the best condition. 



The first indication of reaction against the violen and of an attempt 



to reduce the wideness of the gap appeared immediately after the operation had taken 

 place, the close-lying spines and pedicellariae then being bent over the opening, 

 procedure which even may have been intended to prevent the entram ither 



organisms or foreign particles into the body-cavity. Alter the lapse of about tl 

 hours, the artificial gap was stopped by a thin membrane closing the coelomic cavity 

 from the surrounding medium. By degrees this membrane increased in thick) 

 When viewed with a higher magnifying power, we easily find that, in this case a 

 the amoeboid corpuscles have changed into plasmodia and network, thus producing 

 the membranous covering in question. 



Now it remains to be learnt what the mysterious power is which force, the 

 cells to aggregate in order to fuse together. The white amoebocytes in the Echinoids 

 are, undisputably, capable of gliding slowly along, thus affectuating an actual loco- 

 motion. By means of this faculty, the amoebocytes are enabled to advance nearer 

 to the cells in the neighbourhood in order to fuse together with them, ju 

 shown to be the case when they were crowded in the drop of perivisceral fluid under 

 the cover-slip and brought to a standstill. Of course this motive-power is, however, 

 very limited and is by far from sufficient to explain the fact that the corpuscles in 

 absolute freedom within the coelomic cavity of a large Echinus became 

 at certain places, as for instance, on the cover-slip put into the peritoneal cavity "I a 

 living animal or at the quadrangular opening made in the skeleton. Here we cannot 

 say that they have moved of themselves. 



According to my opinion, the answer lies close at hand. As is known, the 

 perivisceral fluid is constantly in circulation and its corpuscles are kept from fu 

 by the movements of the cilia distributed over the parietes and the viscera. 

 mentioned cover-slip and the quadrangular wound both represent peaceful 

 undisturbed by the powerful currents which encircle them. Very likely the corpus- 

 cles are drifted and accumulated to these spaces in just the same way as drift-w I, 



sea-plants, and masses of organisms are accumulated by the currents at certain i 

 places in the ocean. 



