Views on the Corpuscles of Mammiferous Blood. 369 
obtained—the large cells in the ovum. From these the cor- 
puscles of the blood seem to have descended; and they un- 
dergo changes essentially the same. 
1. The mammiferous blood-corpuscle, like one of the cells 
of the ovum, is at first a disc, or what is now called a “ cyto- 
blast,” z.e.acell-germ. It is not a flattened vesicle or cell. 
Like other discs or cytoblasts, however, it may and does be- 
come a cell; but then it is no longer flat. In the blood-dise 
you see a central, colourless, concave portion, around which 
lies the red colouring matter. 
2. As usually met with, the blood-disc is round, with the 
exception of two or three instances in which, from the obser- 
vations of Manot in France and GuLutver in this country, 
it has been discovered to be elliptical. I have since found 
that even in Mammals where the blood-disc is usually met 
with round, its original form is elliptical. I have seen this to 
be the original form of the blood-disc in Man. 
3. The discs first become round, continuing flat; subse- 
quently they pass into an orange-shape, and lastly become 
globular. They also very much increase in size. 
4. Along with these alterations in the form and size of the 
blood-discs, there takes place another change. Instead of a 
mere concavity, there is now seen a colourless, pellucid, semi- 
fluid substance; which, as the corpuscle becomes orange- 
shaped, is found to be, not in the centre, but on one side. It 
is the nucleus of the corpuscle—the corpuscle itself having 
become a cell. This pellucid substance or nucleus divides 
into and gives off globules.. Each globule, appropriating to 
itself new matter, becomes a disc; and each disc, undergoing 
changes like the first, gives origin to other discs, a group of 
which constitutes the colourless corpuscle of the blood: for, 
with the changes now mentioned, the red colouring matter is 
consumed. ‘Thus, as the red pass into the colourless corpus- 
cles, there must exist all intermediate stages; between them 
no line of distinction can be drawn*. 
5. The corpuscles of the blood are propagated by means 
of parent cells. A parent cell has its origin in a colourless 
corpuscle; this colourless corpuscle being an altered disc. 
* The colourless corpuscles in other Vertebrata, for instance the Batra- 
chians, being much smaller than their red corpuscles, cannot be these red 
corpuscles in an altered state. Nor is any such change to be expected here. 
The red corpuscles usually seen circulating in these animals are not, as in 
Mammalia, discs, but nucleated cells. Some of these nucleated cells, how- 
ever, give origin to discs having very much the same form, size and general 
appearance as the blood-discs of the mammalia. In the Frog I saw such 
discs passing into the state of colourless globules, which, acted on by acetic 
acid, presented just the same appearance as the colourless corpuscles of the 
human subject. 
