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reactions. These considerations, however, Macu and Breuer based 
upon the presupposition that the semi-circular canals are a closed 
system with firm walls and filled with fluid, so that no endolymph 
currents could be expected in progressive movements. In this they 
overlooked the fact, however, that the endolymph of the semi-circular 
canals is connected by the ductus endolymphaticus with the saccus- 
endolymphaticus which lies in the cranial cavity, and also that the 
perilymph is not surrounded everywhere by a firm wall, but that at 
two parts there are elastic membranes, viz. the foramen rotundum 
and the foramen ovale. 
From researches made with the help of a model constructed with 
due regard to the above by Prof. Ornstein and Dr. Bureer, it 
appeared that under these circumstances with progressive movements 
endolymph currents might well occur in the endolymph. 
Thus it remained an open question whether the reactions upon 
progressive mutions are reflexes of the semi-circular canals or of 
the otolithes. 
It therefore became desirable to find a method whereby either 
the canals or the otolithes could be isolated. The latter proved to 
be possible by employing a method of Wirrmaack’s, whereby normal 
guinea-pigs are centrifugated in ether narcosis at a speed of 1000 
metres per minute. Previous to the centrifugation, all the animals 
to be experimented upon were carefully examined as to all labyrinth 
reflexes in accordance with a certain scheme, and the result recorded. 
The same examination was repeated after the centrifugation and 
successively on the following days, so that the complete historia 
morbi of each animal was obtained in this way. A clinical diagnosis 
was then made regarding the condition of the canals and the various 
otolithes, based upon the above-explained views regarding the function 
of the semi-circular canals and the otolithes. After this the animals 
were killed, the labyrinths fixed, and later carefully examined 
microscopically in series-sections. In this way, it was possible to 
compare the clinical and the anatomical diagnoses with each other. 
The results obtained may be summed up as follows; for particulars 
we refer again to the detailed communication to be published later. 
SUMMARY. 
1. By centrifugation of normal guinea-pigs, according to WITTMAACK’s 
method, it was found possible to bring about in many of the animals 
tested a condition in which the labyrinth reflexes upon movement 
are normal (reactions and after-reactions of head and eyes upon 
