268 MiscellatieouH. 



is in the living animal usually observed only in the epithelium of 

 the lower (free) border of the gills (it also occurs pretty fre(]uently 

 in the buccal tentacles) ; but in most cases, over the entire extent 

 of the epithelium, it is possible to witness the penetration of 

 blood-corpuscles, which come from the lacunar connective tissue and 

 are charged with granulations or hyaline spheres of variable, and 

 sometimes very considerable, dimensions. They advance slowly, 

 thrusting out pseudopodia between the epithelial cells, and thus 

 opening a path for themselves to the free surface, where they undergo 

 the same fate as those which leave the lacunae : i. e. they are 

 carried away by the current. The presence of phagocytes among 

 the epithelial cells has recently been mentioned by Dr. Janssens 

 (' La Cellule,' t, ix.). 



It may be asked what is the physiological object of this pheno- 

 menon. Without pretending to solve the question at present, and 

 reserving to myself the right of reverting to it at greater length, 

 I wish to point out one way of looking at it. In preparations 

 fixed by means of Flemming's or Hermann's fluid, I have often 

 discovered, either in the phagocytes, or in the tissues, the presence 

 of degenerate leucocytes. They appeared in the most varied shapes ; 

 but they were always composed of a sphere or of an irregular body, 

 but little or not at all stainable, and serving as a substratum for 

 one or more corpuscles which took a decided saffron stain : the 

 substratum was of protoplasmic origin, the chromatic element 

 was derived from the nucleus. In the same way in the phagocytes, 

 the spheres, which were hyaline in the fresh state, seemed, from 

 their low degree of colourability, to be composed of more or less 

 altered protoplasm. Given these details, the question arises 

 whether it would not be possible to find in the present case an 

 application of the views of Metschnikoff and others, on the subject 

 of a continual strife between the cells of the same organism, 

 which results in the sweeping of the tissues, and in the removal 

 of anatomical elements which are enfeebled, sickly, or decaying, 

 by means of amoeboid cells still in the full vigour of active life. The 

 phagocytes which have come from the depths and contain spheres 

 or coloured matters would have loaded themselves with faeces and 

 dead cells, met with in their diapedeses, and would transport 

 them to the exterior through the epithelium ; on the other hand, 

 the migratory elements which hollow out the epithelium would 

 have been summoned thither by chemiotaxy : the vibratile cells of 

 the lower border of the gill-lamellae are, by their very position, 

 more than all the others exposed to all kinds of destructive 

 influences ; as a cjnsequence they would rajudly become worn 

 out and enfeebled, and their debilitated bodies would attract the 

 leucocytes. 



N.B. — The way in which the tissues thus injured are renewed 

 stiU remains to be examined ; this will form the subject of investi- 

 gations to which I intend to devote myself later on. In conclusion, 

 I do not think it necessary to dwell upon the fact that the lacunae, 

 which have been mentioned so often in the present communication, 

 cannot be confounded with the lattice-like clefts, which permit the 

 passage of the water into the interbranchial spaces. — Comptes Rendus, 

 t. cxvi. no. 2 (Jan. 9, 1893), pp. 65-68. 



