ITS DIFFERENT PHASES OF DEVELOPMENT IN THE ANIMAL SERIES. 
73 
65. Nucleated Blood-cells — Uncoloured stage. — In human blood to which water has 
been added, besides the distended granule-cells, cells of the same size may be seen, 
not containing granules, but presenting most distinctly a single celleeform nucleus 
(fig. / .). Such cells resemble the granule-cell deprived of its granules by the action 
of acetic acid. Moreover, it will be observed that they are essentially similar to the 
nucleated blood-cells in the uncoloured stage of the blood of the mammiferous embryo 
and of the oviparous vertebrate animals. In their mode of development from granule- 
cells, as indicated by the occurrence of cells in transition stages (fig. 10 .) as well as in 
their structure, they are in fact clearly identical. I recognise them therefore as the 
corpuscles in human blood in the phase of nucleated cell, uncoloured stage. 
66. In consequence of the collapsed state into which they fall immediately on the 
blood being drawn (fig. 8.), these uncoloured nucleated cells of human blood are 
scarcely to be distinguished from the collapsed granule-cells (fig. 2 a.) until after dis- 
tention by water. They are usually confounded with them under the same name of 
“ lymph” or “ colourless” corpuscle. 
67 . In the blood of the mammiferous animals which I have yet examined in refer- 
ence to the point under consideration, viz. the Horse, Elephant, Paco, Sheep, Goat 
and Rabbit, uncoloured nucleated cells likewise exist, those of the blood of one ani- 
mal resembling those of the blood of another, and all resembling those of human 
blood in all essential particulars of structure. What difference there is consists in 
the size of the cell, but especially in the size of the celleeform nucleus, as may be 
seen by comparing the figures 9 and 11 of the nucleated blood-cells of the Ele- 
phant and Goat for example ; the celleeform nucleus of the former being about 3 -goo th, 
that of the latter only about 6 ~ooofh °f an inch in diameter. 
68 . Nucleated Blood-cells — Coloured stage. — In the blood of Man unacted on by re- 
agents I have not yet observed such corpuscles, but in the blood of other mammifera 
which I have examined, especially in the blood of the Horse and Elephant, I have 
observed them. Fig. 13 represents one of several such corpuscles observed in the 
blood of the Horse which had been drawn from the animal for a day or two, but to 
which no water or other reagent had been added either before or during the exami- 
nation. The transparent and colourless circumferential ring, the optical expression 
of the transparent and colourless cell-wall doubled on itself, formed a striking con- 
trast with the red-coloured interior of the cell, as did also the uncoloured circum- 
ference of the celleeform nucleus. This nucleated cell differed from the nucleated cell 
in the uncoloured stage in not being collapsed. The one delineated was not plumply 
distended, but others were. Fig. 14 represents a coloured nucleated cell from the 
blood of the Elephant more fully distended. 
69. Fig. 15 a. represents a nucleated cell slightly tinged red, which was observed 
in human blood, but only after the addition of water ; fig. 15 h. represents a still more 
slightly tinged nucleated cell, observed likewise after the addition of water, in the 
blood of the Horse, and figs. 16 and 17 represent similar ones from the blood of the 
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