Dr, Burnett on the Blood-corpuscle-holding Cells. 377 
appear to be aggregations or collections of blood-corpuscles which 
may or may not be invested with a distinct capsule. These cor- 
puscles are in some stage of didingamnicle and appear more or less 
brown, as this dissolution proceeds. ‘hese bodies, Kélliker thinks 
occur very generally and constantly ithe spleen, and he supposes 
that, by them, this orgs n serves for the working up of old worn 
out blood- -corpuscles.* 
need scarcely say that so novel a theory, and one, too, with 
such ostensible plausibility, has attracted the attention and pro- 
voked much discussion among physiologists. Indeed, I know of 
no special subject in physiology, that has received more attention 
from some of the best Microscopists, than this; Remak, Ecker, 
Virchow, ee Reichert, Kolliker, aud many others, have given 
it special attention, and already its literature is not insignificant. I 
cannot here give an analysis of the somewhat different results of 
these observers, but it may be mentioned that although all admit 
that bodies such as I have described, do occur in the spleen, yet 
none of them, as I understand, accept Kélliker’s hypothesis of 
their dunabecis a and all have not observed them with 
that freqnency and constancy mentioned by Kélliker. As for 
myself, I have earef ‘lly examined the spleen throughout the Ver- 
tebrata, with special reference to the doctrine in question. These 
examinations have extended through whole tribes of fishes, rep- 
tiles, birds and mammals. J have “not found jm bodies by any 
means as common as Kolliker has stated ; indeed they have ap- 
peared to me under circumstances which seemed more accidental 
than normal, and, with comparatively few exceptions, they were 
unenclosed by a distinct membraie. This was found to be the 
case especially with birds and reptiles. It is true that with the 
‘rabbit and other rodents which [ have nates these bodies 
were regularly saccular when present, but they were of various 
sizes; and it is worthy of notice that, in cee ania’, blood, 
taken from other parts of the body, showed a disposition toa 
grouping of its corpuscles into masses of variable size 
n some reptiles I have found these bodies present at one time 
and absent at another, and with the frog, where Kolliker says they 
may be beautifully seen, I have generally failed to detect them. 
On the whole, then, my conclusion is, that the bloo ee . 
holding cells of Kalliker, are accidental rather than al p 
ductions, and that they sustain no relatious to the Caidatob of the 
spleen. [regard them as simple, minute extravasations of the 
blood into the spleen parenchyma, which may or may not be in- 
ted with a membrane according to the greater or less plas- 
ticity of the blood. 
* This view Kolliker Reecal oeit in 1847, but it was first enunciated in a complete 
form in 1849, in the art oe 8 the Cyclop, Anat. and Physiol. See literature. 
+ I would except Gerlach, Bitard: see literature, beyond. 
Srconp Series, Vol. XVI, No. 48.—Nov. 1853. 48 
