THE HISTOLOGY OF THE BLOOD OF LARVA OF LEPIDOSIREN PARADOXA. 295 
the rounded daughter corpuscles, and the biconvex disc-shaped corpuscles, are to be seen 
all varieties of intermediate stages. These must necessarily be corpuscles either 
assuming the disc form or rounding up again for division. These intermediate forms 
sometimes possess two centrosomes; sometimes no centrosome can be demonstrated. 
The corpuscles showing early prophase stages of the nucleus always have two very 
distinct centrosomes, and they are either quite spherical (fig. 8, Pl. I.) or are oval and 
often irregular, showing, according to the plane of the section, one or two lateral 
projections (Pl. [. figs. 3 and 4). 
Corpuscles such as that drawn in fig. 4, Pl. I. are frequently met with, in which two 
very distinct centrosomes are present, although the oval nucleus shows still a coarse 
network. 
I believe I am justified in stating that, while it is possible that the corpuscles with 
vesicular nuclei may not divide, at any rate the smaller disc-shaped ones represent the 
resting phase of the dividing cells. 
In the resting stage, if this be so, no centrosome is present in any form in which 
it can be distinguished from the microsomes. 
(2) Nucleus. 
As mentioned above, the nucleus is an oval body. It has a very coarse chromatin 
network (Pl. 1. figs. 1 to 5), with large karyosomes close packed. In a considerable 
number of corpuscles the nucleus is to all appearance a solid mass of chromatin. 
The reactions of the nucleus to the various dyes is interesting. In iron hema- 
toxylin material the chromatin holds the stain with great persistency, so that the 
erythrocyte nuclei are still intensely black after all the other nuclei have completely 
surrendered it. With methylene blue and eosin, the network has a blackish violet 
colour, quite different from the lighter violet of the nuclei of the leucocytes, and again 
from the pure blue of the nuclei of the cells of the mesenchyme. 
The chromatin network again selects the orange from Khrlich’s mixture, and has a 
golden colour. The alveoli are occupied by a delicate green staining, but no linin 
threads can be made out. In a successfully stained specimen the chromatin of the 
mesenchyme nuclei selects the basic dye, and their green colour contrasts with the 
golden yellow of the nuclei of the red corpuscles. 
Notwithstanding this behaviour to the dyes, the rounded masses in the nuclei are 
not true nucleoli, but karyosomes,* or at any rate they are local accumulations of the 
same substance as forms the intervening bars, and, as later, is uniformly distributed 
along the spireme thread. 
(b) Mitosis. 
As I have already stated, no centrosome is to be seen in any recognisable form in 
any of the resting corpuscles, large or small. 
* Cf. Pappenheim, Virchow's Archiv, vol. 145. 
