Miscellaneous. 267 



which all the structural details are seen. I have obtained the best 

 results by using Zeiss' No. 4 eyepiece and F objective (magnifying- 

 power 1010). Under these conditions the globules of the blood 

 appear as little amoeboid corpusculcs with very distinct nuclei. Their 

 protoplasm is sometimes perfectly hyaline, with a few scattered 

 granulations which exhibit an active Brownian movement ; some- 

 times finely granular ; or again packed with hyaline globes of 

 variable dimensions, which may or may not contain in their turn 

 some very refringent spheres. The pseudopodia, which may be 

 seen to appear and disappear, are either numerous and delicate, 

 always perfectly hj'aline and extended in all directions, or else on 

 the contrary isolated, broad, and true lobopodia. It is possible to 

 follow the blood-corpuscles in their peregrinations ; in this way, on 

 the confines of the epithelium, one of these migratory cells is often 

 seen to leave the connective tissue and penetrate between the 

 ciliated cells, separating and depressing them, and thus producing 

 behind it a solution of continuity which goes on increasing. But 

 we soon find that it is something more than a simple separation or 

 depression : the actual substance of the cells is broken into, and 

 exhibits unequivocal signs of alteration. The protoplasm diminishes 

 in places and appears to be eaten away at spots where it has been 

 in contact with a leucocyte. In no case was I able to discover 

 that the amoeboid globule here contained fragments of epithelial 

 colls. The question arises whether we have to deal with digestion 

 at the surface of the leucocyte, or at least with dissolution pre- 

 paratory to digestion. However this may be, a cavity is thus 

 produced which is hoUowed out by the leucocytes at the expense of 

 the epithelium. This cavity continues to increase in size, and soon 

 extends to several neighbouring cells ; it has very distinct limits, 

 which are sometimes exceedingly irregular, and successively assumes 

 the most varied shapes. 



Since it most often happens that the same phenomenon takes 

 place at adjoining spots, the result frequently is that the last 

 remaining cells which still separate the cavities disappear in their 

 turn by the same process ; extensive lacunae are thus formed by 

 means of fusion, in which there move a larger or smaller number of 

 leucocytes, each of which acts as a phagocyte on its own account *. 

 The free jjortion of the ciliated cells is most often intact, and there 

 always persists a border constituted by the fragments of protoplasm 

 which have escaped from the devastation. The body of the phago- 

 cytes grows considerably, in most cases becomes packed with hyaline 

 spheres, and continues to move freely in the lacuna. Here and 

 there they finally cross the border itself at some spot or other, and 

 leave the lacuna to reach the surface of the branchial mucous 

 membrane ; where they are speedily carried away by the current 

 which is produced in the water by the motion of the vibratile cilia. 



The very interesting phenomenon which I have just described, 

 and which, so far as I am aware, has not hitherto been recorded, 



* In these lacunos it is also not unusual to meet with one or more 

 leucocytes which have come from the depths, and are charged with 

 matter of a yellow or dirty brown colour. 



