908 
in physiology also attention was concentrated almost exclusively upon 
this species of labyrinth reflexes. Barany’s attempt to include the 
compensatory positions of the eyeball in clinical research was not 
imitated. 
Besides by pressure, it is a priori very well imaginable that the 
otolithes might react upon motion, if hereby the specifically heavier 
otolithes by reason of their greater inertia undergo slight displacements 
with respect to the underlying sensory epithelium. Macu and BrEUER, 
upon purely theoretical grounds, believed this to be the case with 
the labyrinthine reactions upon progressive movements. Experimental 
data on this point were lacking, but, as it appeared to be physically 
impossible that the canals played any part here, the cause had to be 
ascribed to the otolithes. As will appear below, however, the opinion 
held by Maca and Breuer, namely that for physical reasons the 
canals cannot have anything to do with this, is erroneous, while 
other experimental grounds will be furnished for the theory that in 
the reactions upon progressive movements it is just the semi-circular 
canals that play the chief part. 
As now during the last ten years various other, hitherto unknown 
tonic labyrinth reflexes were found at the Pharmacological Institute 
of Utrecht, it was natural that these new experimental data should 
be used for the further study of the function of the otolithes. For 
this purpose the following method was adopted. If the tonic labyrinth 
reflexes depend upon the greater or lesser pressure of the otolithes 
upon the underlying sensory epithelium, it may be expected that 
these reflexes will be at their maximum or minimum at the same 
moment as this pressure is maximal or minimal. Whether the reflexes 
will be the strongest under the greatest pressure or under the least, 
cannot a priori be stated. This will depend upon whether the sensory 
epithelium is excited most strongly by the pressing or the pulling of 
the otolithes; it might be very well possible that pressure of the 
otolithes gives rise to a certain reflex, whilst pulling might also excite 
another reflex action, though a different one. 
Therefore, to arrive at as unbiassed a conclusion as possible, all 
the tonic labyrinth reflexes were first examined quantitatively as 
exactly as possible, and in particular in what position of the head 
the maximum and minimum of these reflexes were found. 
The tonic reflexes examined were the newly found tonic labyrinth 
reflexes on the muscles of the body and the so-called labyrinthine 
“Stellreflexe’, while further the already long-known compensatory 
“positions” of the eyeball were carefully examined quantitatively 
as to their maxima and minima. This investigation was performed 
