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solution of this specific weight still causes a depression of the 
freezing-point A = — 0,59° C. Ureum penetrates quickly into the 
muscle and makes it soon heavier. Most of the other organic com- 
pounds, which are heavier than water are little soluble, have strong 
viscosity (albumen), are more or less poisonous, irritating or 
anaesthetic. 
I used a mixture of chloroform and benzene of a specific weight 
of 1,041, in which the muscle could be suspended, and I noticed 
several times very distinctly that the muscle lengthened itself again 
after the contraction. As chloroform and benzene are both very 
strong poisons, one is able to observe the muscle only for several 
minutes in this medium. 
] think I may ascribe the fact that these poisons do not affect 
the muscle immediately, to a capillary layer of Ringer’s that wets 
the muscle and through which both the liquids diffuse only slowly. 
Attempts to take a photograph of this phenomenon have not 
yielded beautiful results, owing to little secondary movements of 
the muscle (streams in the liquid through the contraction-push ete.). 
A cinematographic photo would give better results in this respect. 
Looking out for a better recording method, I thought I might be able 
to apply the graphic method, generally used in the muscle physiology, 
though this seemed very doubtful, taking into consideration the 
extremely inconsiderable energy of the dilatation. 
Yet by using an instrument of a minimal mass and friction I 
succeeded in recording a curve (Fig. 1). One sees on this figure a 
fragment of a curve. The upper row are curves of simple muscle 
shocks in Ringer’s liquid, the two following rows are curves of 
tetani in the same liquid. The 4* row is a curve of tetani in a 
mixture of chloroform and benzene. The five lower rows are simple 
shocks in this mixture. All the curves are of the same muscle. The 
steep part of the curve is the contraction, the dilatation is very 
clearly perceptible, but much slower. 
A considerable improvement has been made in this method of 
registration by Professor VAN RIJNBERK, who suggested to me the 
principle of a very useful instrument. It consists of a glass tube, 
with a hole in the side, over which an extremely thin membrane 
of rubber is stretched. A needle is stuck through it, which writes 
with one end on a sooted drum, placed horizontally and with the 
other end is stuck in the Achilles tendon of the frog’s gastrocnemius. 
The other end of the muscle is attached to a hook, which serves 
at the same time for one stimulus-electrode. It pierces a cork, which 
shuts off the tube on one side. Each of these stopcorks is perforated 
