( 715.) 
heat of the different substances into account, which has not been 
done as yet in what precedes. 
Finally we will point out that the above remarks also give us an 
insight into the signification of the theory of the “chemodynamic 
temperature scale” drawn up by Hager in his: “Thermodynamik 
technischer Gasreaktionen”. Haprr is of opinion that for all gas 
reactions for which the number of molecules does not change, the 
same unit of temperature is to be given which makes the constant 
of the equation of equilibrium zero. Because, as we said, both S»H 
and rc, occur in this constant, it is now clear that this comes to 
this that at the temperature 7’= 1 of that scale the same relation 
would hold for ail substances between the size of their “chemical 
volumes” and their specifie heat. A priori little seems to plead in 
favour of the assumption of such a relation. But here too, it will 
only be possible to take a decision by the aid of a kinetic theory 
Which accounts for the variability of the specific heats in connection 
with a very accurate knowledge of the experimental data. 
Physiology. — ‘“Unisegmental vefler-reactions.” By Prof. G. van 
Riunperk. (Communicated by Prof. C. Winkumr.) 
Both in physiology and in clinical work it is hold to be a fun- 
damental axioma of the theory of reflex-reactions, that as the most 
simple expression of the reflexive function may be considered a uni- 
segmental or monomere reflex, where the skinfield receiving the stimulus, 
the afferent nerve-tract, the turning-point in the medulla, the efferent 
nerve-tract and the muscle (or the gland) performing the reaction 
are altogether and exclusively seated within one and the same segment 
of the body and of the medulla. 
The course of the influent dorsal nerve-fibres relative to the cells 
of the dorsal and ventral grey horn (the co-ordinative and the executive 
system), within one single segment of the medulla, apparently may 
be assumed to offer a quite sufficient substratum for a monomere 
reflex. Still, to my knowledge at least, nobody ever had observed 
such a simple reflex, because in all cases where reflexive reactions 
were investigated whose inductive and abdueent nerve-tracts belonged 
to the same nerve-root of the medulla and consequently to the same 
segment of the body, the segment of the medulla serving as turning- 
point, still retained its connection with a larger tract of the medulla, 
and was not therefore isolated anatomically nor functionally. 
For some time I was occupied by the question, whether a 
