114 



NATURE 



yune 6, 1872 



spiralis membranacea, as far as the walls of the canal, thus sepi- 

 rating it into three minor canals. 1 



Between the layers of the membranous spiral lamina are 

 situated the so-called rods of Corti. These were first discovered 

 and described liy the Marquis de Corti ; and although since then 

 many observers have studied the subject, yet scarcely two investi- 

 gators are agreed as to their exact form. 



In a general view of the rods from above, they appear similar 

 to two rows of pianoforte-hammers, rather than like the keys of 

 that instrument, to which they have been likened. In a lateral 

 view, these two rows of rods are seen sloping towards each other, 

 like the rafters of a gabled roof. The rods consist of a shaft 

 and two enlarged extremities, bnt tlie two rows differ considerably 

 in form ; the inner rods are attached by their lower extremities 

 to the membrana basilaris at its junction with tlie lower lip of the 

 limbns, and just external to the spot where the nerve-filaments 

 emerge. They are directed outwards and upwards, witli a sliyht 

 undulation to meet the outer rods. The lower extremity is en- 

 larged and rounded, gradually tapering to the shaft, which is 

 cylindrical ; the upper extremity is sjmcwhat cuboid in form, but 

 the outer surface is deeply concave, and the upper lip of the con- 

 cavity is prolonged into a process. 



The outer rods are attached to the membrana basilaris by a 

 broad base, which also gradually tapers to a cylindrical shaft. 

 Their upper extremity is less cuboid in form, and presents a con- 

 vex internal surface, which articulates with the corresponding 

 concavity in the inner rods just mentioned ; from the outer and 

 upper part there extends outwards a slender process. 



One of the most important features with regard to these rods 

 is their relative length. Most authors state that there is very 

 little difference in the length of the two rods ; in this, however, 

 they are much mistaken ; for not only do the two sets of ruds 

 differ in this respect, but the length of each varies according to 

 its position on the cochlea. Thus, at the base, the outer rods 

 are as nearly as possible equal in length to the inner, but pro- 

 ceeding upwards, both rows increase in length with great regu- 

 larity, although not in the same ratio, the outer increasing with 

 much greater rapidity, so that near the apex they are twice the 

 length of the inner. 



It was generally supposed, a priori, that these rods were 

 graduated so as to distinguish the most minute variation of tone, 

 but no one until now has been able to demonstrate this. 



The rods, therefore, vary in length from about -^Ir, to ^Jj of 

 an inch. The number of rods in each row is not the same, there 

 being about three of the inner to two of the outer, and, according 

 to calculation, there are about 5,200 inner rods and 3,500 outer 

 in the whole cochlea. 



Cx>rti and most other authors considered this system of rods to 

 be the essential portion of the cochlea ; they supposed the rods 

 received the vibrations conducted to them, and being set in mo- 

 tion, so affected the nerves as to cause the brain to appreciate 

 the various sounds. Later German writers have attributed the 

 appreciation of the various vibrations to certain delicate cells, 

 which are attached to the under surface of the membrana reticu- 

 laris. From this circumstance alone it appears very evident that 

 these investigators had not suspected, much less discovered, the 

 fact that the rods are most exquisitely graduated, for otherwise 

 they could surely never have douljted that so beautiful and suit- 

 able an apparatus could have any other ostensible purpose than 

 that of appreciating the various sounds. I consider indeed that 

 the cochlea represents a musical instrument, similar in nature to 

 a harp or musical box, the strings of tlie one and the tooth of the 

 other represented by the rods of Corti. The spiral bony lamina 

 is simply a sounding-board ; around the rods are placed the 

 various nerve cells and nerve-fibres, and from these cells the im- 

 pressions are conveyed by the fibres to the brain itself. 



It is possiljle, therefore, to trace very completely the course of 

 sounds or vibrations from a musical instrument or any other 

 source to the brain, through the medium of the ear. First the 

 vibrations are caught and coUscted by the auricle, and trans- 

 mitted through the external meatus to the drum of the ear, next 

 across the middle to tlie internal ear. Here the sound is ap|)re- 

 dated, merely as a sound, by the vestibule ; the direction is dis- 

 covered by means of the semicircular canals ; but to distinguish 

 the note of the sound, it must pass on to the cochlea. The 

 vibration therefore passes through the fluid cf the cochlea and 

 strikes the lamina spiralis, which intensifies and transmits the 

 vibration to the system of rods. There is doubtless a rod not 

 only for each tone or semitone, but even for much more minute 

 Bub-divisioiis of the same ; so that every sound causes its own 

 particular rod to vibrate, and^this rod vibrating, causes the 



nerve-cells in connection with it, to send a nerve-current to the 

 brain. 



" Examination of the Gases occluded in Meteoric Iron from 

 Augusta Co., Virginia." By J. W. Mallet, Ph.D., M.U. 



The author stated that, whether or not his analysis be con- 

 sidered as furnishing presumptive evidence of the Virginia iron 

 having come to our earth from a different atmosphere to that of 

 which the Lenarto meteorite brought us a sample, the result 

 dillers so far from that of our sole previously recorded determi- 

 nation of the kind as to make it a matter of much interest that 

 a larger number of meteoric irons from various localities should 

 be subjected to careful examination in the same direction, thus 

 supplementing our knowledge of the fixed constituents of these 

 curious bodies by a study of their gaseous contents. 



Anthropological Institute, June 3. — Sir John Lubbock, 

 Bart., presideiit, in the chair. " The artificial enlargement of the 

 Kar-lobe in the East," by J. Park Harrison; " On [Tumuli at 

 Sapolia, Ardaschevo, Russia," by Baron de Boguschefsky ; "On 

 Ogham Pillar Stones in Ireland," by Hodder M. Westropp ; 

 and "The Westerly Drifting of Nomades from the 5th -to the 

 iglh ^century. Part 9 : the Fins and some of their allies," by 

 H. H. Howonh. The object of the paper by Mr. Howorth 

 was, in the first place, to discriminate between the Fins and the 

 Lapps, whose history, physical features, customs, and other 

 idiosyncracies are entirely different. In the second place, to 

 show that the Esthonians belong to the Fin rather than the Lapp 

 stock. Then to adduce the evidence for making both Fins and 

 Esths very recent emigrants into their respective modern habitats, 

 and to trace them to their former country beyond the Dwina, 

 where they were known to the Norsemen as Biarmians, and to 

 the early Ivussian chroniclers as Sarvalokian Ichudes. Having 

 divested Scandinavia and Esthonia of their Fin inhabitants, and 

 having thrust them back into an area which was of great renown 

 in the times of the Norsemen, we can explain how the civilisa- 

 tion, which the Kalevala and other evidence proves, was once 

 peculiar to the Fins, has been lost, and also explain whence the 

 Norsemen derived a great portion of the culture which dis- 

 tinguished them. The main position that was new in the paper 

 was the deriving the Esthonians from the same area as the old 

 Fins, and making them also to be recent emigrants, and not 

 Autochthones, as they have been so frequently described ; and 

 the clearing up of the ethnography of the old province of 

 Biarniia, which has hitherto been much confused. 



Victoria Institute, June 3. — The Rev. Prebendary Irons 

 read a paper on Prot. Tyndalls " Fragments of .Science for Un- 

 scientific People. " lie first dealt with physical science and its 

 rivalries. Dr. Irons holding that there was a want of thorough- 

 ness in Prof Tyndall's appeal to facts. He then analysed the 

 statements made as to the action of matter on matter, and con- 

 sidered Dr. Tyndall to be inconsistent in stating that science 

 could not solve the problem of the Universe, and yet adding that 

 we ought not to see the evidences of Divine pleasure or dis- 

 pleasure in the phenomena of the material world. Finally, Dr. 

 Irons urged that science and true religion could not be supposed 

 as opposed to each other, as some men of science would have us 

 believe. 



Cambridge 



Philosophical Society, May 27. — " On some properties of 

 Bernoulli's numbers, and, in particular, on Clausen's Theorem 

 respecting the fractional parts of those numbers," by Prof J. C. 

 Adams. The author gave a comparatively simple projf of 

 Clausen's theorem. Thirty-one of Bernoulli's numbers are already 

 known ; the author has calculated twenty-two additional num- 

 bers. He also had proved that if n were a prime number other 

 than 2 or 3, the numerator of the «"' Bernoulli's number was 

 divisible by ;/. — "On some of the Symptoms produced by 

 Urtemic Poisoning in Chronic Disease of the Kidney," by Dr. 

 Latham. These symptoms were explained by : — i. The im- 

 peded passage of the blood through the minute arteries of the 

 system, caused by excessive contraction and hypertrophy uf the 

 muscular walls of these vessels, as has been demonstrated by Dr. 

 George Johnson. 2. The hypertrophy of the heart, developed 

 by the resistance offered to the circulation from the' contraction 

 of these small arteries. 3. The impoverished state of the blood, 

 which is the necessary accompaniment of the disease. 



Canterhurv 

 East Kent Natural History Society, May 2. — "Remark- 



