Agglutination of the Blood Corpuscles in Ganiniarus 249 



which causes vibrations and upheavals of portions of the clump. The ap- 

 pearance at this stage calls to mind that of an active volcano belching forth 

 stones and cinders, some of which get piled up round the crater, while every 

 now and then the whole mass is shaken and torn hy the eruption of 

 material from the centre. No portion of the adhering mass of cells gets 

 torn away, however. When once the cells stick in the mass thej' remain 

 firmly attached. 



This flow from the central tunnel soon ceases, and the clot becomes 

 entirely closed in by the adhesion of the cells all around. The mass which 

 they form is at first porous and still allows of the escape of plasma, though 

 the corpuscles which are carried down the filament to the spot are held 

 back and become piled in a column inside the portion of the filament near 

 the wound. The piling up may extend back over one or two segments, but 

 not as a rule very far, for a way of escape for the corpuscles is found in one 

 of the cross capillaries, and now the venous circulation begins again as if 

 nothing had happened. 



This whole process takes from a minute to two or three or more minutes 

 according to the thickness of the portion amputated. A wound in the very 

 end of the filament is naturally closed up sooner than one nearer the proximal 

 end. Once the internal plugging of the vessel has occurred, the terminal 

 clot may be removed without any further risk of bleeding. Often enough 

 animals may be found in which for some reason or other a whole antennary 

 filament has become filled with a mass of corpuscles. Amputation of such 

 a filament produces no bleeding. 



The cells which form the terminal clump do not long retain their 

 rounded shape. During the time that the blood is still escaping they 

 undergo changes in shape, becoming at first wrinkled and still later losing 

 their outline and fusing with neighbouring cells. This fusion may have 

 taken place in the cells which lie nearest the cut surface of the filament 

 even -at the time when other corpuscles are still escaping from the end. 

 When the bleeding stops it is not long before the whole clump becomes 

 felted into one irregular mass in which no outline of any cell is visible. 

 At the same time the mass is seen to have become somewhat shrunken. 

 Whether it is one special form of cell among the white blood corpuscles 

 that contributes to the formation of the clot, or whether all forms get caught, 

 I have not yet determined. 



This method of observing the agglutination of the cells in bleeding is 

 simple and retjuires little manipulative skill : it might well be adopted for 

 class demonstration. The animals are readily procured, and the process may 

 ])e repeated two or three times on the antennas of the same specimen. 



