April 4, 1895J 



NATURE 



551 



the frequency of this tone 2, i.e. the first difference tone, or is 

 it I, which corresponds to the first term of the Fourier series 

 for the periodic disiurbance ? In tlie chords 2 to 3, 3 to 4, 4 

 to S, &c., the difference of the intfgers lieing unity, the first 

 difference tone is identical with the first Fourier tone. When 

 the difference of the two integers which express the chord is 

 not unily, then the writer considers that experiments he has 

 made with strings and pipes, show that the first Fourier term 

 is usually the only combination tone that is audible. Prof. S, 

 P. Thompson considered that care should be taken to define 

 what we mean by the subjective or objective existence of a note. 

 There are two very delicate methods which have already been 

 employed for detecting the existence of a given note in the air. 

 (l) The formation of ripples on a soap-film stretched over the 

 opening of a resonator tuned to the rttjuircd pilch (.Sedley 

 Taylor) ; (2) the sounds produced in a telephone connected to 

 a microphone placed on a thin elastic membrane slretched over 

 the neck of the resonator (Lummer). It was very important to 

 limit our acceptance of the demonstration of the objectivity of 

 combination tones, given by the authors of the paper, to the 

 case actually proved, i.e. to tones produced by the polyphonic 

 siren. It did not necessarily follow that if pure tones produced 

 by tuning-forks were used, the srime results would be 

 obtained. A number of experiments had been made 

 by Zanledeschi in 1S57, in which two notes were 

 sounded, and skilled musicians were asked to record 

 their impression of the third tone present. In 75 per cert, cf 

 the cases the note recorded was the difference tone ; in the 

 remaining25percenl.it corresponded to Kiitnig's b'at tone. 

 Kbenig himself had never heard the summation tone in the case 

 of lightly-bowed forks. Voigtin a theoretical paper has shown 

 that if there ,-ire two disturbances whcse mean kinetic energy 

 difftr, the Ilelmhollz tones will be produced; but that if the 

 mean kinetic energy of the two disturbances are equal, the 

 Helmholtz effects soon die out, and you get beat tones or beats. 

 He (Prof Thompson) considered that Dr. Burton had allowed 

 his perception of tone to be governed by the quality of the role, 

 and that the apparent lowering of pitch was due to ihe variation 

 in the intensity of the overtones present. In reply to Prof. 

 Thompson, Dr. liurton said he did not merely perceive a lower- 

 ing of pitch, but he was able to estimate the change in pitch, 

 and say at what instant, as the vibrations of the fork died out, 

 Ibe lowering amounted to a lone or half a tone, &c. Mr. Boys 

 said he found that by careful atlemlon he could apparently per- 

 suade himself that the note in Dr. Burton's experiment was 

 lowered or raised in pitch, or that it remained unaltered. A 

 similar effect in the case of the eye could be obtained with a 

 stereoscopic picture. The Chairman considered that, while 

 Helmholtz' explanation of the pioduclion of combinalion 

 tones might be real, it did not follow that this explanation gave 

 the sole cause of their formation. In particular, Helmholtz 

 does not explain w by the tones should only be produced by some 

 sources of sound. Prof Riicker, in his reply, said he did not 

 deny the existence of Koenig's beat tones ; in fact, he had heard 

 them. Tliey did not lay much stress on Ihe negative result of 

 the experiment they had made to test the objective existence of 

 these heat tones. 



Zoological Society, March ly. — Sir W. H. Fluwer, 

 K.C.B., F.R.S., Pre.-ident, in the chair.— Lt.-Col. H. H. 

 Godwin-Austen, F.R.S., presented a paper on behalf of Mr. 

 Walter E. Collinge, and himself, " 'in the Structure and Affi- 

 nities of some new Species of Molluscs from Borneo." Three 

 new species were described, viz. Daniayattita ^mithij lilicropar- 

 mariou pclloiicrai, and M. limrolhi. Iictails were given of 

 their structure and com|-arisons instituted with other members 

 of the genera and allied Indian genera. One of the most in- 

 teresting features, perhaps, was the similarity they show an.ito- 

 mically to shell-bearing molluscs of Borneo. That these slug- 

 like forms of Borneo have the same close relalionsh'p to the 

 shell-bearing mollusca among whom ihcy are now found living, 

 as the Indian forms bear to Macrochlawys and allied shell- 

 bearing genera, there can be little doubt, and any true attempt 

 at classification must be based on these lines, and would place 

 a wide gulf between Cirasia and Austeiiia on the one side, and 

 Parmaricn and Rlicrof-armarion on the other. — Mr. F. E. 

 Beddard, F.R.S., read a preliminary account of new species of 

 earthworms belonging to the Hamburg Museum. These worms 

 belong cbielly to ihe genera A(anll:oJiiliis and Alicroscolex, 

 and had been collected in South America. — Prof. F. Jeflfrey 

 Bell communicated, on behalf of I'rof Alphonse Milne- 



NO. 1327, VOL. 51] 



Edwards, Jardin des Plantes, Paris, the description of a new 

 species of crab of the genus llyailentis, obtained near the 

 Straits of Magellan during the Challenger Expedition, and pro- 

 posed to be described as //. comobrinus. — Dr. A. G. Butler 

 gave an account of two collections of Lepidoplera received by 

 the British Museum. One from Zomba, made by Mr. J. 

 McClounie, remarkable for Ihe number of specimens of the fine 

 Butterfly genus Chara.xrs it contained. The other made at 

 Fwambo, Lake Tanganyika, by Mr. .Vlexander Carson, in- 

 teresting as including rot only rare species previously only 

 received from Zomba and Lake Mweru, but several novelties, 

 the finest of which was Junonia pavonina, a new form allied 

 to /. arlaxia. — .Mr. P. Chalmers Mitchell read a paper in which 

 he gave a description of the provinlricular crypts he had found 

 in a specimen of the African Tantalus {Pseudotaiitaius il>is) 

 recently livirg in Ihe Society's Gardens. 



Entomological Society, March 20. — Piof. Raphael 

 MeUlola, F.R.S., President, in the chair. — Mr. H. St. John 

 Donisthorpe exhibited a living female of Dytiicus iiiarginaiis, 

 with elytra resembling those of the male insect. Dr. Sharp, 

 F.R.S., said he had seen this form before, but that it was very 

 rare in ihis country, though abundant in some other parts of the 

 paljearctic region. Prof. Stewart asked if the genitalia had been 

 examined. Mr. Champion stated ihat Mr. J. J. Walker had 

 collected several females of an allied species (Dyliscus circum- 

 /le.xiis) at Gibraltar with elyira resembling those of the male. — 

 Dr. Sharp exhibited specimens of Hrenlhiis aitc/iorago, from 

 Mexico, showing extreme variation in size. He remarked that 

 the males varied (rom loi mill, in length 1051 mill.; the female 

 from 9^ mill. 1027 mill. In the male the width varied from ij 

 mill, to 4 mill. The length therefore varied from about 5 to i, 

 and the width from 3 to i in the male. — Mr. Blandford com- 

 mented on the difficulty of mounting minute Lepidoplera, Dip- 

 tera, Neuroptera, &c., and exhibited samples of stripsof material 

 which he had found most suitable for the purpose of staging 

 minute insects. He said his attention had been called to this 

 method of mounting by Ihe receipt of specimens from Dr. Fri£, 

 of Prague. On examination of the material he found it to be a 

 fungus, J'otyfoi us leiiilitiiis. He stated ihat Lord Walsingham 

 had expressed his satisfaction wilh this material, and had sent 

 him specimens, similarly mounted, from /eller's collection. 

 Mr. McLachlan, F. R.S., remarked that he thought the material 

 exhibited preferable to artichoke pith, which had been used for 

 a similar purpose. — Mr. Goss exhibited a specici of a Mantid, 

 J'iaidocreobotra Wahlbergi, Slal, received from Captain Mont- 

 gomery, J. P., of Mid-Ilovu, Natal. — Mr. Frederick A. A. 

 Skuse communicated a paper, entitled " On a colour variety of 

 Heteronymfhtt metope. Fab., from New Soulh Wales," and 

 sent coloured drawings of the typical form and the variety for 

 exhibition. — Mr. Oswald H. Latter read a paper, entitled 

 " Further notes on the secretion of polassium hydroxide by 

 Dicranura viniila (imago) and similar phenomena in other 

 I.epirioptera." The paper was illustrated by the oxyliydrogen 

 lantern. Prof. Meldola congratulated Mr. Latter on the 

 thorough way in which he had worked out his experiment, 

 and said that in view of the small quantity of material at his 

 disposal, the concordance in the results was remarkable. He 

 added that Mr. Latter had, for the first time, proved the secre- 

 tion of free potassium hydroxide in the animal kingdom. Mr. 

 Blandford, Mr. Merrifield, and Dr. Dixey continued Ihe dis- 

 cussion. — Mr. Merrifield read a paper, entitled "The results 

 of experiments made last season on Vanessa C-album and 

 Limenitis Sibylla." This was illustrated by an exhibition of 

 specimens of /,. sibylla, and a long series of V. Calbiim, to show 

 the effects of temperature in producing abnormal forms. Dr. 

 Dixey said that many of the forms of V. Calbum exhibited re- 

 minded him of /'. Caurcum, a Chinese species, which he be- 

 lieved to be one of Ihe oldest forms of the genus. He thought that 

 much of the variation shown in this series of specimens was 

 due to al.ivism, and was not directly attributable to the eflfect 

 of temperature. Mr. Barrett said he was interested to find that 

 one of the forced forms of /.. sibylla was similar to a specimen 

 he had seen which had emerged from the pupa during a thunder- 

 storm. In ccnnection with Mr. Meirifield's paper, Mr. F. W. 

 Frohawk exhibited a scries of 200 specimens of V. Calbum, 

 bred fiem one female token in Heicfordshire, in April 1894. 

 The series consisted of 105 malts and 95 females, and included 

 41 specimens cf the light foim, and 159 of the dark form. 

 Piof. Meldola, in proposing a vote of thanks to Mr. Merrifield, 

 Dr. Dixey, and Mr. Frohawk, said that he was glad to think 



