Physiology. — “Kvperimental proof for the active dilatation of 
cross-striated muscle-tissue’. By J. BRAMSON. (Communicated 
by Prof. G. van RIJNBERK). (After experiments made in the 
Physiological Laboratory of the University of Amsterdam). 
(Communicated at the meeting of January 31, 1920). 
We are accustomed to observe that a muscle, after contraction, 
regains its original length by mechanical influences from without. 
So in situ, by contraction or tonus of antagonists, and outside the 
body by gravitation, eventually by weights, stretching the muscle. 
In 1871 Luciani’) discussed the question whether dilatation of a 
muscle was an active process. He wanted to explain the diastole of 
the heart partly by the active dilatation of the myocard. 
We need not be surprised in the least that tissue dilates actively, 
when we only think of the formation of pseudopodies in the case 
of amoebes and leucocytes. 
But it was not thought possible however that cross-striated muscle 
tissue could regain its original length by its own force, because a 
muscle, put on mercury, does not lengthen again after contraction. 
In 1900 Kaiser *) pointed out that the frog’s sartorius lengthens 
again actively on mercury, when oiled. He thought he had proved 
the active dilatation by this. 
To this however an objection was raised, not without reason, 
that every particle of the muscle, owing to gravitation tries to place 
itself as low as possible and yields to this impulse, as soon as the 
contraction of the muscle ceases. It expands on the mercury as 
much as possible and thus it becomes longer again. 
Consequently the problem acquired a different aspect. The muscle 
had to lengthen itself, while it was withdrawn from the gravitation. 
This is possible by bringing it into a liquid of the same specific 
weight as the muscle has, viz. of 1,041. 
The difficulties, connected with this, are very great. A salt- or 
sugar-solution of specific weight is not isotonic. Even a raffinose 
1) L. Lucranr. Dell’ attività della diastole cardiaca. Rivista clinica Bologna. 
2) K. Karser. Ueber die Wiederausdehnung des kontrahirten Muskels. Centralbl. für 
Phys. XIV p. 195, 
