1364 
after which such isomorphous erystal-structures would sessess similar 
space-lattices, in which simply a substitution of one atom-species by 
another closely related one has occurred, appears to be highly 
probable and well justified. 
hb. However it cannot be denied, that under the same, or at least 
extremely similar circumstances of the experiment, there appear to 
be not only differences between the corresponding patterns in their 
minor details, but especially in the nwnber and in the characteristic 
relative distribution of the intenstties of the spots, which can only 
be accounted for by assuming differences in the specific secondary 
radiations, which are typical for every kind of substituting atoms 
especially. 
It is not impossible, however, that e.g. the more or less close 
occupation of corresponding reticular planes in those space-lattices, 
will moreover play a certain role in the whole phenomenon. 
Laboratories for Physics and for General and 
Inorganic Chemistry of the University. 
Groningen, February 14'> 1916. 
Physiology. — “On the function of the m. obliquus superior of 
the eye’. By Dr. C. Orro Rorzors. (Communicated by Prof. 
Dr. G. Van RIJNBERK). 
(Communicated in the meeting of January 29, 1916). 
The m. obliquus superior takes its origin at the foramen opticum 
between the m. rectus superior and the m. rectus internus. The 
muscle runs medially in the top of the orbita to the front, over the 
m. rectus internus; near the trochlea the round tendon bends and 
is then directed posteriously and towards the temple. Then the 
tendon becomes flatter, is continued under the extremity of the m. 
rectus superior to attach itself in the shape of a fan to the temporal 
superior quadrant of the posterior bulbus-half. The line of insertion 
runs more or less from nasal posterior to temporal anterior. 
The direction of the part of the tendon between the trochlea and 
the point of insertion into the surface of the bulbus is with this 
muscle of great importance for the mechanism of the motion. 
Therefore we must know the exact location of the trochlea and of 
the point of insertion into the bulbus. To Fick must be given 
credit for having first indicated, how we can determine by asystem 
of coordinates the points of origin and insertion of the muscles of 
