THE HISTOLOGY OF THE BLOOD OF LARVA OF LEPIDOSIREN PARADOXA. 307 
number in differentcells. In many they are scattered very sparingly through the 
protoplasm (fig. 27, Pl. III.), in others they are closely packed (fig. 29, Pl. II1.), while in 
a smaller number the whole cell body is a uniform mass of closely apposed large granules 
of nearly uniform size (fig. 30, Pl. III.). These last-described corpuscles may be 
classified as 
(4) Eosinophil Leucocytes. 
Though they have all the appearances of eosinophils described in adult animals, it 
is not contended that they necessarily belong to the same category. 
In leucocytes in which the granules are sparingly distributed, their dimensions vary 
from the minutest particle to bodies 2 to 4 « in diameter. They are highly refractile, 
and this gives rise to some ditfliculty in determining their relations to the meshwork. 
In the drawings I have represented them as seen surrounded by their halo of refraction. 
Apart from their actual relationships to the alveoli of the meshwork, it is quite 
certain they are not the nodal points of a reticulum, but are clearly metaplastic, 
probably minute drops in the protoplasm, which run together to form larger granules. 
Exactly similar granules are found in the yolk cells, so that it is probable that these 
in the leucocytes are derived from that source, in which case they could be neither 
secretory nor excretory products; but to this question I shall return in the second part 
of this memoir. 
There is always a space clear of granules round the centrosome (figs. 29 and 31, 
Pe 1iT.). 
The nucleus varies greatly in shape, but in its other characters it agrees with that 
of the mononuclear leucocytes. The simplest form in which it is found is the horse- 
shoe shape (Pl. Il. fig. 19; Pl V. fig. 49). Between this and the complicated lobed 
condition there are all varieties. Sometimes it is ring-shaped (Pl. V. fig. 47), while 
sometimes it is formed of quite a number of lobes (PI. II. fig. 20; Pl. IIL. fig. 27). 
In no case are the lobes detached from one another to produce a multinucleated cell. 
They are always joined by attenuated portions of the nucleus. The leucocyte figured 
in fig. 27, Pl. ILI. has all the appearance of a polynuclear cell, but careful scrutiny 
proved that the several lobes were connected together like the two lobes of the nucleus 
seen in fig. 29 on the same plate. 
I have found all the varieties of the leucocytes in mitotic phases, but these are few 
in number at the stages examined compared with the dividing erythrocytes. The 
polymorphonuclear may divide with the nucleus in the horseshoe form. The general 
character of the karyokinetic phases is the same as in the erythrocytes, but the chromo- 
somes arising from a relatively loose and scantier chromatin reticulum are much finer 
and smaller, and the achromatic structures are of great delicacy. It is interesting to 
note that, as has been observed in other cases, the centrosome which is so large in the 
resting phases is reduced during mitosis to a very fine granule, hardly to be demonstrated. 
As the object of the present writing is more descriptive than theoretical, I do not 
TRANS. ROY. SOC. EDIN., VOL, XLI. PART II. (NO. 11). 46 
