( 550 ) 
Physiology. — Prof. Pekelharing offers a communication, also in 
the name of Dr. C. J. C. van Hoogenhuyze : “ About the for¬ 
mation of creatine in the muscles at the tonus and at the 
development of rigidity” 
(Communicated in the meeting of December 24, 1909). 
On a preceding occasion ») in this Academy I have made a com¬ 
munication concerning an investigation by Mr. van Hoogenhuyze and 
Mr. Verploegh about the excretion of creatinine in man, from which 
it, appeared that the excretion of this substance in a sufficiently nourished 
person was not increased by muscular labour. Since that time the 
investigation, which promised new results, now that a good method for 
the determination of the creatinine had been furnished by Folin, has 
been continued by Van Hoogenhuyze and Verploegh and by several 
others. From these investigations has arisen the opinion that, through 
the consumption of protein in the tissues of vertebrate animals, 
creatine is formed, and that this' matter is partly decomposed under 
oxidation, partly, particularly by the liver, changed into the anhy¬ 
dride, creatinine, that further the creatinine thus formed is for the 
greater part removed from the body through the kidneys a ). 
If this opinion is correct, one cannot but assume that the creatinine 
excreted by the kidneys, originates for the greater part from the 
creatine of the muscles, not only because the muscles are richer in 
creatine than other organs, but also because it is especially the mus¬ 
cles which contain so considerable a part of the proteins which the 
body contains. This supposition did not seem unacceptable, notwith¬ 
standing it has been found that the excretion of creatinine is not 
increased by muscular labour. Observations were made which pointed 
to a connection between the excretion of creatinine and another 
phenomenon, which has to be distinguished from the muscular con¬ 
traction in a narrower sense, the muscular tonus. Van Hoogenhuyze 
and Verploegh found the excretion during the night to be smaller 
than in the daytime; likewise did they find remarkably little creati¬ 
nine in the urine of old men and of patients who had a number of 
muscles paralyzed, whereas in case of fever the urine appeared to 
contain more creatinine than usual. 
That really the tonic shortening of the muscle is brought about 
in another way than in case of rapid contraction, which has been 
examined so much more, and that, when a single stimulus is followed 
i) Proceedings of the meeting of 80 Sept. 1905. 
S) See : Zentrallbl. f. d. ges. Physiol, und. Pathol. d. Stoffwechsels. 1909. No. 8. 
