951 
July 1. 1919 we found: 
Blindfolded the animal (in the air) has completely lost its sense of orientation. 
Pelvis held on its right side: Head held on its right side. (Fig. 1). 
Pelvis held on its left side: Head held on its left side. 
Pelvis held on its back: Head held on its back. 
Suspended with head downwards: Head held on its back. 
Suspended with head upwards: Head retro- or latero-flexed. 
Not blindfolded (i.e. with eyes open) the animal presents quite another image. 
Pelyis held horizontally on its left or right side: Head in normal positions. 
(Fig. 2). 
Pelvis held horizontally on its back: Head in normal position, the front of the 
body flexed ventralward, the animal fixing his surroundings with great interest. 
Suspended with head downward: Considerable flexion of the head towards the 
back, muzzle upwards and head in normal position. 
Suspended with head upwards: Head in normal position. 
The above observations and other investigations of various dogs 
not reported here, tend to show that the dog, held up in the air, 
completely loses ifs sense of orientation directly after bilateral ex- 
tirpation of the labyrinth, but also that after a few days it gradually 
learns by the aid of his eyes to bring its head into the normal 
position. Already after two or three days this ability begins to 
appear; it is almost complete after a week and quite accomplished 
after about a fortnight. 
lt is noteworthy that the development of optic “Stellreflexe” could 
be traced in a dog, of which on Dec. 4 1918 Dr. Dussur Du BARENNE 
had removed the greater portion of the cerebellum, so that at the 
post-mortem only the frontal part of the vermis and small remnants 
of the cerebellum were found laterally from the medulla oblongata. 
When pr KrevN on March 3rd 1919 had performed on this animal 
the bilateral extirpation of the labyrinth, no trace of “Stellreflexe” 
could be observed during an investigation on the 28rd of April and 
on the 26 of May, when the animal was held up free in the air 
with bandaged eyes. On the other hand the optic ‘‘Stellreflexe” were 
