45 
microscopical anatomy by bringing the blood changes into 
relation with a structure to which such a function has never 
been ascribed. Kdlliker had, many years ago, with a sort of 
divination, expressed the opinion that the origin of the red 
blood-corpuscles from the white in the adult organism would 
never be demonstrated until nucleated coloured cells should 
be discovered. It was reserved for Neumann, not only to 
discover the long-sought cell, but also to establish, on several 
grounds, its character as a transitional form. 
The views of Neumann are published in the ‘ Archiv der 
Heilkunde,’ vol. x. (1869), p. 68, e¢ seg., under the title, 
“The Significance of the Marrow of Bones in the Formation 
of Blood.” He there lays down two propositions : 
1. There takes place in the vessels of the bone-marrow, 
favoured by a considerable retardation of the blood-current, 
a transformation of abundantly-accumulated white cells into 
red. 
2. A continuous passage of medullary cells into the vessels 
contributes to this accumulation of white cells in the blood- 
vessels of the marrow. 
This whole theory, for which a considerable number of 
more or less reliable arguments can be urged, gains at once 
a large amount of probability from the discovery, first, of the 
coloured nucleated cells, and, secondly, of a remarkable accu- 
mulation of lymph cells in the marrow, in virtue of which 
the latter acquires an impertance with regard to the forma- 
tion of blood, not only equal, but greater than that formerly 
ascribed to the spleen. Other important arguments are, how- 
ever, alleged. Neumann has found beside those nucleated 
and coloured cells, which he regards as the true intermediate 
form between the white and the red corpuscles, other transi- 
tional forms which, on the one hand, form a passage from the 
white blood cells to the red nucleated cells, on the other 
hand, from these to the red non-nucleated corpuscles. 
Neumann meets the objection that these coloured transi- 
tional cells may be merely lymph-corpuscles tinged with 
blood colouring matter, by showing that their general charac- 
ter is quite different from that of lymph-cells, and further, 
that they are limited to the osseous marrow. He accordingly 
compares them, as well as similar forms met with in the 
frog, to the nucleated red cells of the embryo. 
The detailed description given by Neumann of the marrow 
refers especially to the marrow of the bones of rabbits, and he 
regards the existence of similar relations in the human body 
as a matter of probability rather than of certainty. 
Eales also has found these minute structural characters of 
