38 
tion, and seems to have held the view, so 
far as the testis is concerned, that the ma- 
terial furnished to the blood is absorbed 
from the external secretion and is normally 
carried off in part in this secretion. 
During this same period the brilliant re- 
sults of the experiments made upon the 
thyroid glands and the pancreas were forc- 
ing themselves upon the attention of physi- 
ologists, and these results, together with 
his own experiments upon the extracts of 
testis and ovary, and his previously ex- 
pressed belief as to the possible effect exer- 
cised by all glands upon the composition of 
the blood, seem to have led Brown-Séquard 
to the generalization expressed in the 
happy term ‘internal secretion.’ The term 
as used by him was not restricted to the 
glandular tissues alone, but was meant to 
signify that all the tissues in the body fur- 
nish something of special importance to 
the blood—that, in fact, every act of nu- 
trition is accompanied by an internal secre- 
tion This broadening of the term to apply 
to all the tissues is logical, perhaps, but it 
must be admitted, I think, that so far as 
our actual knowledge goes it is not justifi- 
able. The evidence derived from experi- 
mental investigations and clinical observa- 
tions indicate that many, although not all, 
of the glandular tissues of the body as a 
result of their normal metabolism add 
something to the blood or affect its com- 
position in some way, and that this ac- 
tivity is either essential or helpful to the 
maintenance of the normal functions of the 
organism. In this list we can place such 
glands as the liver, pancreas, thyroid and 
parathyroid bodies, suprarenal bodies, hy- 
pophysis cerebri, and probably the ovary, 
testis, thymus and spleen. But I know of 
no observations that force us to entertain a 
similar belief with regard to the non-gland- 
ular tissues, such as muscle, nerve and 
connective tissue. 
So far as I am aware, there is no author- 
SCLENCE. 
_ thyroid and testis. 
[N.S. Vox. VI. No. 182. 
ized definition of the term internal secre- 
tion, but, if we adhere closely to the facts 
in the case, the expression may be in- 
terpreted to mean certain products that are 
elaborated by gland cells from material 
furnished by the blood, which are after- 
wards passed back to the blood or lymph 
stream to subserve some function in general 
or special nutrition. From the standpoint 
of mechanism of secretion a useful distine- 
tion has been drawn between these internal 
secretions and secretions of the usual kind, 
or external secretions. The latter are in all 
typical cases poured out upon a free epithe- 
lial surface that communicates with the ex- 
terior, while the internal secretions are dis- 
charged upon the close endothelial surfaces 
of the blood and lymph vessels. 
The definition given by Brown-Séquard, 
as we have seen, attributed internal secre- 
tions to all tissues. Asa part of this gen- 
eral conception he was led also to restate 
what appears to have been a dream of the 
older physicians, namely, the view that all 
animal tissues might and ought to be em- 
ployed in special cases as means of medical 
treatment, extracts of each organ or tissue 
being recommended for the particular dis- 
ease supposed to be due to disturbance of 
function in the corresponding tissue. This 
general conclusion seems to have been a 
wide induction upon the basis of the incom- 
plete facts known at that time with regard 
to the therapeutical use of extracts of 
It was not entirely 
justified by actual experience then or now, 
but the attractive possibilities it presents 
have doubtless been the cause of much of 
the general interest manifested in the sub- 
ject of internal secretions. A new field, 
hitherto almost unexplored and full of 
promise for the discovery of medical spe- 
cifics, seemed to be opened to the medi- 
cal profession, and much activity has been 
exhibited in exploiting the possibilities of 
this kind of therapeutical treatment for 
