Dr. Burnett on the Blood-corpuscle-holding Cells. 379 
I think there can now be but little doubt that the systematic 
position of the spleen is in the category of ductless glands,—be- 
longing, as to its physiological signification, with the Supra-renal 
capsules and the Thymus and Thyroid bodies. Its structure and 
its development, both, indicate the correctness of this view. 
Experiments have shown that, whatever may be its function, 
the presence of the spleen is far from — indispensable in the 
body or even necessary for its health.* whole history of its 
formation and development i in the embryo, Jeane shows that it 
the a of incubation is over. 
Its relations to the conan then do not begin until ii animal 
has commenced to have a nutrition of its own. In this respect, 
therefore, it is inverse to the other duetless glands; fos: as has 
been well shown by Ecker and other observers, the Thymus and 
Thyroid bodies, and the Supra-renal capsules, are truly embryonic 
organs, and cease to perform any function in the individual animal. 
I would, therefore, say that the whole tenor of present research 
upon this organ, combined with many incidental pathological 
phenomena, favor the view that the spleen has functional relations 
in the adult life, corresponding to those of the other ductless 
glands, just mentioned, in the embryo; that is, it is intimately 
connected with the formation of the red-corpuscles of the blood. 
I would not say with Gerlach and Schaffuert that it is the locality 
where these SE aa are formed,—but rather that it has more 
the office of a lymphatic gland where the plastic materials of the 
blood are prepared and unis fence for their conversion into the 
red- -corpuscles ; or, to speak more to the point, it is one of the 
organs in which isle ugascien: are formed and eliminated bee 
paratory to their being changed into, or rather serving as the basis 
for the formation of, the true red- -corpuscles. The Malpighian 
Vesicles are undoubtedly prominent agents in these processes, and 
Gray has shown that their development here is precisely like that 
of the vesicles in the Thymus and Thyroid glands. In this con- 
nection should also be mentioned the fact of the existence of the 
spleen is most prominent in those vertebrates which have the 
ted constituents of the blood most marked, while with the Myxi- 
* The sensible remark of Haller is well worthy of quotation in this connection 
“In utilem aliquam partem corporis animalis esse, tam laté per divisas species r 
nantem, indignum est dictu.”—. physiolog. vi, 426. ‘ 
{Se rey On Oe evelopment of the dct on -waercngpronties gg Philos. 
Trans, 1852, part ii, ; t See literature, beyond. 
