No. I.] THE VERTEBRATE EAR. 69 



conclusion was that both theoretical considerations and the 

 embryological data were against the nervous nature of these 

 spiral bands of threads. 



In his earlier account of some points of cochlear anatomy, 

 Nuel (207) described in great detail the system of spiral nerve 

 fibres, and noted the following important fact which vitiates 

 the theory of spiral nerves in the organ of Corti : " Eine 

 Merkwiirdigkeit von diesen Fasern muss ich noch erwahnen, 

 namlich auch in Bezug auf diese Faden finden wir das System 

 der Horzellen in den ausseren Stutzzellen vorgebildet, dem ich 

 fand ein ganz identisches System von spiralen Fasern zwischen 

 den Stutzzellen, die, wie gesagt, den Horzellen schon analog 

 gelagert sind." 



The fact that the so-called spiral nerve bands are well devel- 

 oped in connection with non-sensory cells casts doubt upon their 

 nervous nature. I believe the "spiral nerves" exist in the 

 living condition as delicate walled but relatively large lymph 

 channels which are formed between the bases of the cells, and 

 which are found not only in the organ of Corti and the Saurop- 

 sid organ, but also in the organs of the lateral line and the sense 

 organs of the ears of fishes. In Petromyzon such a lymph chan- 

 nel is well developed in the surface canal sense organ (PI. VIII, 

 Fig. 11), and I have figured the lymph vessel under the inner 

 row of outer hair cells of the pig on PI. Ill, Fig. 10. There are 

 numerous moniliform threads shown here, but they are part of 

 the wall of the lymph space, and are not nerves, but connective- 

 tissue fibres. These lymph spaces contract under the influence 

 of reagents along with the other parts of the organ, and then 

 appear in cross section, not as intercellular spaces, but as granu- 

 lar bodies placed on or near the bases of the hair cells ; and this 

 appearance is what Retzius has figured in sections of the mam- 

 malian cochlea. The fibres do not stain in Dogiel's methyl 

 blue, and osmic acid does not differentiate them from other 

 fibres of undoubted connective-tissue nature. The varicose 

 fibres have appeared most distinct under low powers and after 

 alkaline reagents. Finally, the evidence of comparative anatomy 

 is entirely against the existence of these spiral nerve bands. 



From the foregoing account of the cochlear ridge in the 

 Hydrosauria and in the Mammalia it appears that a large num- 

 ber of cells outside of the last row of external hair cells seem 



