965 
two modifications, the appearance of the substance does not show 
that we are dealing with a metastable system. Consequently, if 
the physical constants of this system should be determined, various 
values would be found, which would depend on the previous thermal 
history of the substance. 
If this system is kept without special precautions, the material 
soon takes up enough water to be transformed after some time 
into the «modification. I hope to report shortly on the quantitative 
side of these phenomena. 
SUMMARY OF RESULTS. 
From the above it is evident that: 
1. The non-metals as well as the metals, which are produced 
from their melts without special precautions are metastable systems 
in consequence of allotropy *). 
2. That the chemical compounds as well as the elements are 
metastable systems in consequence of polymorphy *). 
3. That the physical as well as the mechanical constants of all 
solid substances, as hitherto known are fortuitous values; these 
being functions of the previous thermal history *) of the substances, 
and they have to be redetermined with the pure «-, B-, y- 
modifications. 
Utrecht, June 1915. van ’r_ Horr-Laboratory. 
Anatomy. — “On the vagus and hypoglossus area of Phocaena 
communis’. By Dr. H. A. VERMEULEN. (Communicated by 
Prof. Bork). 
(Communicated in the meeting of November 27, 1914). 
Nucleus motorius dorsalis vagt. This, for nearly ?/,, stretches out - 
spinally from the calamus. (Series of 493 sections of 15 u, 138 being 
spinal and 255 frontal from the calamus, figs 1 and 7). It appears 
with a few small cells (12—15 u) dorsally from the lateral portion 
of the canalis centralis, which exhibits at this place on section 
the form of a groove running horizontally, fairly wide in the 
middle and pointed at the sides. It is quite obliterated; a normal 
1) This is also the case with substances showing dynamical allotropy. 
8) This is also the case witb substances showing dynamical isomery. 
8) Strictly speaking: a function of the previous thermal, electrical, photochemi- 
cal. . . . history, or generally, of the whole previous history. 
