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It was evident, then, that in the biceps as well as in the triceps 
the amount of kreatinin had been reduced in default of the tonus, 
slight though the reduction may be. This result confirmed our pre- 
vious experience viz. that reinforcement of the tonus was followed 
by an increase of the amount of kreatin. 
This experiment by itself can hardly be said to yield conclusive 
evidence. We should not even have communicated it, if it had not 
led us to extend our inquiries in a somewhat different direction, as 
we were struck by the fact that also the two normal muscles of 
this eat contained only a relatively small quantity of kreatin. Our 
earlier estimations showed that the triceps brachii of the cat con- 
tained in 5 cases an average of 3.397 mgr. of kreatinin per 1 gr. muscle 
(max. 3.902, min. 2.963). It has been demonstrated by several ob- 
servers that, in general, the amount of kreatin in corresponding 
muscles of the same species, so long as the animals are under 
normal conditions, is not subject to considerable fluctuations. 
We could hardly suppose that, with our cat, the amount of kreatin 
in the muscles of the right foreleg should be lowered in consequence 
of the cutting of the centripetal nerve roots at the left side. We 
may still add that the nutritive condition of the animal had left 
nothing to be desired up to the day of its death. 
Our attention was then arrested by a circumstance which perhaps 
would furnish some explanation. For certain reasons, irrelevant to 
the matter in hand, the cat, which had always been free in its 
movements, had been locked up in a hutch during the last two 
weeks of its life. This Hindrance to the animal’s movements might 
have occasioned a weakening of the muscular tonus in general and 
consequently a lowering of the content of kreatin also in the normally 
innervaied muscles. With a rabbit this restraint may be altogether 
ignored, because a rabbit usually “sits” in its narrow hutch and 
thus, no doubt, keeps many of its muscles in tension. The cat, on 
the other hand, being accustomed to move about freely, lies down 
quietly after a short period of restlessness and relaxes its muscles, 
even when awake. Now though it must be admitted that the study 
of the muscular tonus is still in its initial stage and though we 
do not yet fully understand the collaboration of tonus and rapid 
contraction, we may take it for granted that most likely the alter- 
nate contractions are accompanied by a reinforcement of the tonus, 
either in the contracting muscles or in the antagonists, or in both. 
We, therefore tried to ascertain the content of kreatin in the 
muscles of cats which for some time had been hampered in their 
movements. 
