66 MR. T. WHARTON JONES ON THE BLOOD-CORPUSCLE CONSIDERED IN 
18. The conclusion to be drawn from what has now been said in regard to the 
relationship between the granule blood-cell and the nucleated blood-cell is, that they 
are to be viewed as two different phases of development of the same body, the granule- 
cell being the Jirst phase of development , the nucleated cell the second phase of 
development. Each phase of development again comprehends two principal stages : 
the phase of granule-cell, a coarsely and finely granular stage ; the phase of nucleated 
cell, an uncoloured and, a coloured stage. 
19. In the osseous fishes which I have examined for the purpose, the blood-cor- 
puscle in its phases and stages of development is essentially the same as in the 
Skate. In the Lamprey also, which is a cartilaginous fish lower in the scale than 
the Skate, the blood-corpuscle in its phases and stages of development is the same, 
with the exception that the nucleated cell in its coloured stage is circular, as well as 
that in the uncoloured stage (figs. 4 a, 3.) # . 
20. It is worthy of remark, however, that there is a fish, the lowest of the lowest 
division, in which the blood is perfectly colourless, viz. Branchiostoma lubricum., 
Costa, Amphioxus lanceolatus, Yarrell-|~. The corpuscles of the blood of this fish 
have not been examined, but there can be little doubt that some of them are the 
same as the granule blood-cells of the Skate or Lamprey, and others the same as 
the nucleated blood-cells in their uncoloured stage. If this be so, the blood of Bran- 
chiostoma lubricum would differ from that of other fishes, merely in the absence of 
nucleated cells in the coloured stage. It is quite possible, however, although the 
blood appears perfectly colourless, that nucleated cells in the very commencement of 
the coloured stage may exist. 
21. From Fishes I now proceed to Reptiles, and as an example of a Reptile I take 
the Frog, in which to examine the blood-corpuscle. 
Examination of the Blood-corpuscles of the Frog, and a comparison of them with those 
of the Skate. 
22. In the blood of the Frog, as in that of the Skate, the following kinds of cor- 
puscles are to be recognised: — granule-cells and nucleated cells; the former in 
coarsely and finely granular stages, the latter in uncoloured and coloured stages. 
23. What are usually spoken of under the names of “ lymph,” or “ colourless” 
corpuscles, are the granule-cell in both its stages, and the nucleated cell in its un- 
coloured stage. The relation of these corpuscles to the lymph will be considered in 
Part Second of this paper ; here I view them as corpuscles existing in the blood, and 
therefore as blood-corpuscles : blood-corpuscles, moreover, differing from each other 
* Professor Rudolph Wagner was the first to point out the circular form of the red blood-corpuscle of the 
Lamprey, but he does not appear to have noticed the existence of a nucleus. 
f Muller, Mikroskopische Untersuchungen liber der Bau und die Lebenserscheinungen des Branchiostoma 
lubricum, Costa, Amphioxus lanceolatus, Yarrell. Auszug aus dem Monatsbericht der konigl. Preuss. Aka- 
demie der Wissenschaften zu Berlin, Dec. 1841. 
