80 MR. T. WHARTON JONES ON THE BLOOD-CORPUSCLE CONSIDERED IN 
in a more or less marked manner two principal stages, a coarsely and a finely gra- 
nular stage. In all the animals examined we likewise find blood-corpuscles in what I 
call the second phase of development, or phase of nucleated cell ; this again present- 
ing two principal stages, an uncoloured and a coloured. In Branchiostoma lubricum 
alone of all the oviparous Vertebrata, we have seen reason to conjecture (par. 20.) 
that the nucleated blood-cell occurs in the uncoloured stage only, or if a coloured 
stage exists, that the coloration is only in a very slight degree. 
99. In regard to the nucleated blood-cell in the coloured stage, it is to be observed 
that it occurs in its highest degree of development and in great number only in the 
oviparous Vertebrata, in which it constitutes the “ red corpuscle,” and in the early 
mammiferous embryo. In the fully-formed blood of the Maminifera it occurs in a 
comparatively low degree of development, and in very small number. 
100. It is in the Mammifera alone that we find the blood-corpuscle in what I call 
the third phase of development, or phase of free cellseform nucleus*. This exists in 
both uncoloured and coloured stages. In the former stage it is rare, in the latter it 
is the “ red corpuscle” of the fully-formed blood of Man and the Mammifera. In the 
early mammiferous embryos which I have examined there have always been, in addi- 
tion to the numerous “red corpuscles” similar to those of the oviparous Vertebrata, 
i.e. red nucleated blood-cells, some “ red corpuscles” similar to those of the fully- 
formed mammiferous blood. Is there a period in the development of the mammi- 
ferous embryo when there exist in the blood no such “ red corpuscles,” viz. free cel- 
leeform nuclei in the coloured stage ? 
The summary now given will be found both tubularly and pietorially illustrated by 
the Plate. 
Part II. 
In this part of my subject, I purpose to examine the corpuscle of the lymph of 
vertebrate animals, and to compare it with the corpuscle of their blood. 
The Corpuscle of the Lymph of the Shate and Mackerel. 
101. The lymph of the Skate examined was obtained from the orbit in very small 
quantity, and could not be considered a good specimen. The corpuscles were be- 
sides a few granule-cells, nucleated cells in the uncoloured stage, — the cell-wall of 
many extremely pale, — and some nucleated cells in the earlier stage of coloration, — 
all identical with the corresponding corpuscles of the blood of the animal. (See 
figs. 1 to 6.) 
102. The lymph of the Mackerel, taken as an example of an osseous fish, was like- 
wise obtained from the orbit, and might be viewed as a good specimen. It contained 
granule-cells, nucleated cells in the uncoloured stage, — many with the cell-wall so 
pale as to be readily overlooked without attentive examination, — and nucleated cells 
* Free nuclei, which may he met with in the blood of oviparous Vertebrata, are to be looked upon as mere 
abortions of a third phase of the blood-corpuscle. 
