49 
ON THE CONTRACTILITY OE TENDONS. 
By M. Guerin. 
In this memoir M. Guerin calls into question the accuracy 
of the doctrine which regards the tendon as a mere passive 
instrument for the transmission of motion. He has long 
been of opinion that it is possessed of contractility, although 
of another description to that inherent in muscular structure. 
ITe thus sums up the results of his observations : 
1. Histological facts, — M. Guerin long since demonstrated 
that, under certain determinate conditions, such as constant 
and excessive tension, a muscle may pass into the fibrous 
state, resembling, in every histological particular, its tendon, 
of which it now forms but a mere prolongation. Able micro- 
scopists have repeatedly found themselves quite unable to 
distinguish between the two. From this identity of structure 
he was led to infer identity of function. Moreover, he, as 
well as other surgeons, had observed that muscles, evidently 
in a fibrous state prior to an operation, the result of which 
was the restoration of their normal length and tension, fre- 
quently, in the course of years, or even of months, regain 
their fleshy condition. 
2. Pathological facts enable us to establish directly the con- 
clusions proceeding from the above induction. In 1840, M. 
Guerin first proved that tendons are susceptible of a special 
retraction, independently of the muscle properly so called ; 
that is to say, that they may become and remain shortened, 
as a consequence of a kind of spasm limited to their sphere 
of action. This, besides being met with in various lesions 
implicating only the tendons (as in certain burns, abscesses, 
&c.), is of frequent occurrence, and easy to recognise in rheu- 
matic and scrofulous affections of the joints. 'The anatomical 
character of tendinous retraction, distinguishing it from the 
retraction of the muscle properly so called, is the diminution 
of the length of the tendon in relation to the muscle, which 
preserves its normal length. The contrary takes place when 
the muscular fibre primarily participates in the retraction, or 
is its principal seat. The retraction originates in a lesion and 
pain localised near the insertion of the tendon, as in certain 
arthralgias, under the influence of which an attitude of the 
joint is assumed in relation to the action of the shortened 
tendons, without participation of the muscles properly so 
called. Such attitude has been supposed to be assumed 
voluntarily in order to obtain relief from pain ; but an in- 
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