34i 
PROFESSOR POUCHET, 
of Other organs which have not the same anatomical 
structure. 
The Marrow of the Bones . — Of all the questions which 
touch upon hsematogenesis, perhaps the most delicate and, 
moreover, the most difficult to settle, is the part which is 
played by the marrow of the bones. Just now this haemato- 
poietic function, which has been attributed to so many 
organs one after anotlier, is ascribed to the marrow of the 
bones ; and it must be admitted there are more or less valid 
reasons for it. In the first place, in all mammals, with- 
out exception, the marrow of the bones preserves the charac- 
ters which it has in the foetus, that is to say, the marrow 
remains red, particularly in the bodies of the vertebrae.^ 
Even in mammals which have a large quantity of fat, 
e. g. Cetacea, I have ascertained that the marrow of the ver- 
tebrae and the spongy substance of the large bones of the 
limbs is red ; lastly, the red marrow cannot be removed from 
an animal in the way the spleen can, and the part it plays 
in haematogenesis experimentally judged. 
In 1868 there was a dispute between MM. Neumann and 
Bizzozero, as to who had discovered in the red marrow of 
animals anatomical elements, the protoplasmic body of which 
presented the same characters as the substance of the haema- 
tids, but which at the same time possessed a nucleus. 
Stated thus, this fact, as pointed out by MM. Neumann and 
Bizzozero, is perfectly correct, but MM. Neumann and Biz- 
zozero, each on their own side went further, and' concluded 
that the red marrow was essentially haematopoietic, and 
that the elements that they pointed out were none other than 
young haematids in the course of development. This in- 
terpretation may he true, but it is not yet proved. To accept 
this hypothesis we must take it for granted that haema- 
tids are formed by the atrophy or haemoglobic degeneration 
of the true cells of the marrow, and that they fall, after their 
nucleus has completely disappeared, into the blood-stream, 
just as the nuclei of origin fall (as I have shown above) into 
the lymph stream. 
The first question that then suggests itself is — have the 
capillaries of the red marrow any walls ? M. Hoyer, 
and more recently M. G. E. Rindfleisch, have declared 
that the medullary capillaries possess a wall. Moreover, 
M. Rustizky showed, in 1872, and I have since proved, 
that the medullary capillaries are certainly coated with endo- 
thelial cells. 
’ Excepting in the last caudal vertcbrse, where on the contrary it is ex- 
tremely full of fat. 
