44. 
spleen and lymphatic glands, for which the abundance of 
those elements in the vessels leading from these glands is a 
weighty argument. It has, however, always been a matter of 
the greatest difficulty to determine in what part of the body 
the metamorphosis of the blood-corpuscles takes place. This 
process also has been referred to the spleen, and especially 
on the strength of two peculiar structures met with there— 
(1) cells resembling the white blood-cells, but with a yellow- 
ish colour; (2) cells said to contain red blood-corpuscles. 
The first form undoubtedly exists, as confirmed by Eales, in 
the rabbit’s spleen, but loses in importance when compared 
with the more characteristic transitional forms observed by 
Neumann. The second form of cell at first excited great 
interest, but its occurrence is so very variable and uncertain 
that it is probably correct to regard it, with Virchow, as a more 
or less pathological structure. 
It has also been supposed that the metamorphosis of 
blood-cells may take place in the liver, and this because the 
red corpuscles of the hepatic vein are thought to show, by 
their greater resistance to the action of water, that they are 
younger than those of the portal vein, which are not only 
swollen up, but completely destroyed, by the addition of 
water. ‘There are also many crenated and withered red cor- 
puscles to be seen in the portal vein, but very few in the 
hepatic. These facts, if they prove anything, rather tend to 
show that the corpuscles in the portal vein are old and worn 
out, than that those in the portal vein are new; and the well- 
known solvent power of the biliary acids for the red cor- 
puscles makes it probable that these may be destroyed in the 
liver and help in the formation of bile. But there is no proof 
that any new corpuscles are formed in the liver. 
This enumeration is sufficient to show that, as regards the 
adult organism, no single point in the development of blood- 
corpuscles is yet satisfactorily established. Even that for 
which the most cogent arguments may be brought forward, 
namely, the origin of white blood-cells in the spleen, has 
recently met with the renewed opposition of Henle; who 
suggests, however, no other theory in its stead. 
Professor Neumann, of Konigsberg, deserves the credit, 
not only of having, more or less, overthrown the theories 
hitherto proposed of the development of the blood-corpuscles, 
but also of having successfully inaugurated investigations on 
this point which lead in an entirely new direction. He has 
pointed out, as Henle did, that the organs which have been 
up till now considered are comparatively unimportant, and 
has most successfully filled up the gap thus produced in 
od 
