No. I.] THE VERTEBRATE EAR. 163 



der Masse von der Seite betrachtet das bekannte streifige 

 Aussehn." 



" Selbstverstandlich wird die Cicpida durch die vorgenommene 

 Behandlung der Objecte beeinflusst, aber ebenso sicher ist es 

 auch, dass man aus dem bestimmten, der Umgebung angepass- 

 ten Verhalten dieses so verbreiteten Aufsatzstuckes auf den 

 Sinneshiigeln schliessen muss, die Natur liefere dafur schon 

 eine Grundlage, welche gewiss nicht ohne Bedeutung fiir die 

 Function ist." Our author was not able to find the cupula in 

 the lateral canals, if we except a single instance when he 

 observed " nur ein unregelmassiges, faseriges Gerinnsel," and 

 he accounts for this condition by assuming that the cupula 

 secretion is too thin to stick to the sense organ. It is impor- 

 tant to note, however, that he did find the hairs much longer in 

 the sense organs of the lateral canal than in the other struc- 

 tures, where he found the cupulas well developed. 



If, as he assumes, in harmony with the rest of the cupula 

 defenders, this is a secretion of compound nature poured out 

 between the hairs and surrounding them with a jelly-like sheath, 

 it is fair to ask what becomes of the older portions of the cupula 

 as additions are made to its base. For it is evident that this 

 secretion must go on continuously if secretory cells, as holders 

 of this view claim, are present among the sensory cell group. 

 It would be necessary to assume a constant resorption of such 

 mucoid secretion. Now, while there is no question that some 

 mucus is present in all cases (all in which exact analyses have 

 yet been made), there is no evidence to show that in a state of 

 nature it exists as a dome-shaped mass covering the sense 

 organ. On the other hand, it is clearly proven that the most 

 typical cupulae yet studied are products of the action of reagents, 

 and that so far as fibrous structures in the channels occupied 

 by sense organs {whether ear organs or those of the lateral line 

 system) are concerned, they have in every thoroughly studied 

 case shown themselves to be hairs more or less unchanged. 

 Fritsch concludes by explaining that the free access of water 

 to the lateral canals would wash out the mucoid cupula which, 

 in the case of the vesicles of Savi and of the ear, would be 

 retained. 



The special form of sense organs, known under the name 

 of Savi's vesicles, have a peculiar interest for us at this time, 



