( 551 ) 
by a slow contraction, the two ways collaborate, is rendered very 
probable. , , 
Already more than 20 years ago Grutzner 1 ) made the supposition 
that the long continued contraction was brought about by another 
kind of muscular fibres than those which cause a more rapid con¬ 
traction. In the first case fibres of the type of the red, in the second 
fibres of the type of the white muscles, were supposed to be brought 
into play. Afterwards others, more particularly Bottazzi *), have 
defended the theory that the double contraction is caused by two 
different component parts of the same muscular fibre, the rapid by 
the double-refracting fibrils, the slow ones by the sarcoplasma. 
Mosso*) had objections against this theory and drew attention to the 
double innervation of the muscular fibres, not long ago once more 
made clear in this Academy by Boeke 4 ). 
Meanwhile, whatever the opinion may be, at any rate there is 
some reason to assume that the contractions of two kinds must be 
accompanied by a chemical action of two kinds. Now that in the 
usual muscular labour, which is principally based on rapid and 
tetanic contractions, no increase in the consumption of protein and 
in the excretion of creatinine was found, it might be asked, whether 
perhaps in the tonic contraction formation of creatine in the muscles 
could be proved. 
That under certain definite circumstances the muscles at their 
contraction yield more creatine to the blood than otherwise, has 
already been found by Weber 6 ), with respect to the heart treated 
after Langendorff’s method and beating in Ringer’s solution. He 
also found a considerable increase in the excretion of creatine with 
a dog, after violent cramps had been caused in the animal with 
cinchonine. Not only in the last case, in which the animal or 
an hour “was in violent tonic and clonic cramps , but also• With 
respect to the heart taken from the body, it may be assumed that 
tonus has played a part. 
However in order to draw more certain inferences, we have 
examined the quantity of creatme in muscles, under circumstances 
which, as much as possible, allowed to judge about the influence, 
either of tonic, or of rapid contractions. 
J ) Pflvger’s Archiv. Bd. XL1, S. 280. 
2) Journ. of Physiol. Vol. XXI, p. 1, Arch. f. PhysioL 
de Biol. T. XL1I, p. 169. 
S) Arch. Ual. de Biol. T. XLI, p. 183. 
4 ) Proceedings of the Meeting of 23 April 1909. 
5 ) Arch. f. exp. Path, und Pharm. Bd. LVIII, S. 93. 
1901, S. 377, Arch. ltal. 
