74 MR. T. WHARTON JONES ON THE BLOOD-CORPUSCLE CONSIDERED IN 
Sheep and Paco. These may be looked on as transitions from the uncoloured to the 
coloured stage of nucleated cell, such as have been above referred to in the blood 
of the early mammiferous embryo and in that of the oviparous Vertebrata. 
70. Having thus demonstrated, besides granule-cells both in coarsely and finely 
granular stages, nucleated cells, both in uncoloured and coloured stages, in the 
fully-formed blood of the Mammifera, as well as in their early embryonic blood, 
though in much smaller number and of a much less deep colour as regards the cells 
in the coloured stage*, I now come to inquire into the nature of the well-known 
“ red corpuscles” of the fully-formed blood of the Mammifera. 
71. “ Red Corpuscle ” of the fully -formed blood of Man and the Mammifera. — In con- 
sequence of similarity of colour, it has been generally taken for granted that this is 
the exact analogue of the “red corpuscle” or coloured nucleated blood-cell of the 
oviparous Vertebrata. Physiologists have accordingly supposed that it should contain 
a nucleus ; but though unsuccessful in the attempt to demonstrate one, they have not 
altogether ceased to believe in the existence of an exact analogy between it and the 
“red corpuscle” or coloured nucleated blood-cell of the oviparous Vertebrata; they 
have rather had recourse to conjecture to account for the absence of a nucleus. 
72. In reference to this point, the red nucleated cell of the blood of the early mam- 
miferous embryo has been especially appealed to; it being considered by Mr. Gul- 
liver, and I think correctly, as the exact analogue of the “ red corpuscle” or coloured 
nucleated blood-cell of the oviparous Vertebrata. But to take it for granted that 
the “ red corpuscle” of the fully-formed blood of the Mammifera is the exact 
analogue of the red nucleated cell of their early embryonic blood, is not more war- 
ranted than to take it for granted that the “ red corpuscle” of the fully-formed blood 
of the Mammifera is the exact analogue of the red nucleated blood-cell of the ovipa- 
rous Vertebrata. 
73. Under the impression however that the “red corpuscle” of the fully-formed 
blood of Man and the Mammifera is the exact analogue of the red nucleated cell of 
the blood of the early mammiferous embryo, Mr. Gulliver endeavours to account 
for the absence of a nucleus in the former by supposing that it disappears at an early 
period of intra-uterine life. This apology for the absence of a nucleus in the “ red 
corpuscle” of the fully-formed blood of Man and the Mammifera, would have had 
weight if the “ red corpuscle” had been an object persistent throughout life like a 
limb or an eye, but as it is an object constantly disappearing and being regenerated, 
we should expect, if it were really a nucleated cell originally, to meet with it in a 
stage when it does contain a nucleus. 
* It is proper to mention that an appearance simulating that presented by the circumferential doubling of 
the cell-wall and by the slightly coloured interior of the nucleated cell, coloured stage, of fully-formed mam- 
miferous blood, may be produced by the diffraction of the light around any corpuscle. As the diffracted shadows 
referred to however are always concentric with the corpuscle, error from this source may with certainty be 
avoided by the unpractised observer in all those cases at least, in which the cellaeform nucleus is situated eccen- 
trically within the cell. 
