THE HISTOLOGY OF THE BLOOD OF LARVA OF LEPIDOSIREN PARADOXA. 305 
have the same yellow tint as the karyosomes, showing that the material for the 
chromosomes is at any rate chiefly drawn from them. 
Though in the great majority of sections the nucleus appears spherical, it is more 
than probable that corpuscles showing characters identical in other respects, but with 
a notch at one pole, as represented in fig. 25, are merely cells cut in a plane at right 
angles to that in which the rounded nucleated cells are cut. I have observed, however, 
all degrees of notching, from a slight bay to an angular depression, such as seen in 
fig. 25, or even to a linear fissure reaching to the centre of the nucleus, the two 
walls of which are in close contact. In sections such as that drawn in fig. 25, 
Pl Ill. there is found lying opposite the notch a very imperfectly developed 
centrosome. I have drawn it as a nearly circular darker portion of the protoplasm, 
which is the ‘attraction sphere,’ staining like the protoplasm a neutral tint with 
triacid. At the centre is a slightly darker circular spot, which I take for the 
centrosome, but it is impossible to make out either a radial structure in the ‘sphere’ 
or rays extending from it into the surrounding protoplasm. In iron hematoxylin 
and eosin preparations the same spot in the cell comes out as a homogeneous area, 
staining of a darker red tint than the rest of the cytoplasm, but I have never seen 
a darker spot in its centre. 
There is no doubt that we have here to do with a protoplasmic area, which 
corresponds to the area to be described in the next variety of leucocyte, showing an 
active and operative centrosome, with its attraction sphere and rays. 
In triacid preparations the protoplasm stains of a somewhat indefinite neutral 
tint, and no granules are ever to be made out. 
The cell represented in fig. 25, Pl. ILI. is certainly a leucoblast, but there is some 
reason to believe that certain of the cells like that figured in fig. 24, Pl. II]. bear a 
relation to the EryrHropuasts. These are cells of the same dimensions, but with 
larger karyosomes and a coarser intervening network, and showing a concentric fibrilla- 
tion of the basiphil protoplasm. They will be dealt with in Part II. 
(3) Polymorphonuclear Corpuscles. 
This variety I have named in keeping with the general terminology of blood histol- 
ogy, on account of the lobed form of the nucleus. This body may, however, have many 
forms (as seen in figs. 19, 20, Pl. II.; 27-29, Pl. III.; and photographs 46, 47, 48, 
Pl. V.). Sometimes, as in fig. 27, Pl. III., the superficial appearance is that of a 
multinuclear corpuscle, but in reality the nucleus of that cell was single, but much 
lobulated. 
This group of corpuscles is characterised by the possession of a well-marked 
centrosome in active operation. They are frequently seen in active diapedesis. 
Further, they always show, or almost always show, granules in their protoplasm. I 
shall first describe the centrosome. In fig. 19, which is the same cell photographed 
in fig. 49, I have drawn the body without filling in the granular cytoplasm. 
