The Structure and Functions of the ha?molymph Glands and Spleen. 33 



are to be obtained by staining- sections of tliese glands in luemaluni 

 and eosin, on account of the well known attraction of red cells for 

 eosin. This method gives a bright contrast between the red cells, 

 the blue of the hcienialum and the yellow of the pigment. 



I have attempted in my figures (pi. I. fig. 11) to give typical 

 illustrations of the process of phagocytosis; all the stages with the 

 exception of one (pi. I. fig. 11 d) were drawn from the same slide. 



Vincent and Harrison^) first suggested that, in the haemal glands, 

 a phagoc3Ì:e, \)j a method similar to that adopted by an amœba in 

 feeding, may ingest several (as many as 20) erythrocj^tes. They 

 supposed that the ingested cells are subsequently attacked, and 

 eventually transformed into the pigment, which they found both in 

 the cells and free in the sinuses. 



Schumacher's-) description was more detailed. He observed a 

 vacuolation, not only in the phagocyte, but in the ingested red cells 

 themselves. The vacuoles of each erj^-throcyte, he described as running 

 together, so that ultimately a single vacuole remained, of the shape 

 and size of an erythrocyte. I am unable to confirm these observations 

 of Schumacher. In cover glass preparations vacuoles certainly abound, 

 but such a preparation is not altogether satisfactory, as the mere 

 drying of the film, or the friction produced by the cover glass, is quite 

 sufficient to produce appearances easily mistaken for vacuoles: in fact 

 many other specimens prepared by this method show a distinct vacuo- 

 lation in many cells, though such is not normally the appearance. In 

 sections, however, vacuoles do certainly exist, but these have only 

 been observed, with very few exceptions, in the interior of cells 

 containing little or no pigment. Moreover in these vacuoles are fre- 

 quently seen unaltered blood corpuscles (pi. I. fig. 11 c). I consider 

 the vacuolation due to the fact that where one or more blood cells 

 are engulfed by the psuedopodia of a phagocyte (assuming that it 

 ingests erythrocytes or other food particles after the manner of an 



^) Log. cit. 



-) Loc. cit. It is to be remembered that Schumacher described phagocytosis 

 in "Lymphdrüsen" and apparently was unaccpiainted with any special form of the 

 glands such as hœmal or haemal lymphatic. 



Internationale Monatssclirift für Anat. u. Phys. XX. 3 



