49 
8. More decidedly yellow, somewhat smaller; without 
nucleus. 
9. Yet smaller; more intensely coloured, without nucleus 
(ordinary red blood-corpuscles). 
It will be seen from this short description of the different 
cell forms, that they constitute so unbroken a series that one 
might be tempted on this basis alone to refer the meta- 
morphosis of blood-elements without hesitation to the 
marrow ; if, however, there were no confirmatory grounds, 
the author would not venture to draw this conclusion, since 
the cells in question might be susceptible of another inter- 
pretation. 
The process of transformation appears to be, judging from 
the series of forms above described, as follows: — The 
lymph-corpuscles diminish from the periphery, next they lose 
near the centre some scattered granulations, while the re- 
maining hyaline substance begins to be coloured yellow so 
soon as the granulations have quite disappeared, though with 
little general diminution in the size of the cell ; the nucleus, 
previously granular, becomes small and homogeneous — 
while the whole cell is still but little diminished in size,— 
and it is not till the nucleus has first broken up and then 
quite disappeared that the size of the cell is materially 
diminished. 
Neumann, who refers to this process only in the following 
words, “The protoplasm becoming coloured and at the 
same time homogeneous ;—after that disappearance of the 
nucleus,” does not seem to understand the process of trans- 
formation quite in the way here sketched out, and draws 
especial attention to cells which are more or less homogeneous 
in the centre, but retain their granular character at the 
periphery. If, however, these represented transitional forms 
on their way to become red corpuscles, there should be also 
forms with a yellow coloration in the centre, which is not 
the case. Hence these forms described by Neumann may 
perhaps not be transitional forms at all, but rather modifica- 
tions of the ordinary lymph-cells which are on their way to 
perish altogether. ‘The probability that some do thus perish 
before conversion into red corpuscles has already been pointed ° 
out by Virchow. 
With respect to the frequency of these transitional forms, 
they may be found in larger or smaller numbers in the fluid 
from all red marrow; at least the characteristic nucleated 
coloured cells have never been found entirely wanting. 
Examinations have been made of the bodies of new-born 
children and adults of every age, including, in one case, a 
VOL. XI,—NEW SER. D 
