542 



NATURE 



[April 6, 1893 



shall get the result stated. The curve obtained in this 

 way is in reality identical with the other curves. By these 

 four methods then we arrive at the conclusion that the 

 last colour to be extinguished is the sensation which when 

 strong gives the sensation of violet, but which when feeble 

 gives a blue-grey sensation. 



One final experiment I may show you. It has been 

 remarked that moonlight passing through painted glass 

 windows is colourless on the grey stone floor of a cathe- 

 dral or church. 



We can imitate the painted glass and moonlight. Here 

 is a diaper pattern of different coloured glasses, and by 

 means of the electric light lantern we throw its coloured 

 pattern on the screen. The strength of moonlight being 

 known, we can reduce the intensity of the light of the 

 lamp till it is of the same value. When this is done it 

 will be seen that the pattern remains, but is now colour- 

 less, showing that the recorded observations are correct, 

 and I think you are now in a position to account for the 

 disappearance of the colour. 



I have now carried you through a series of experiments 

 which are difficult to carry out perfectly before an 

 audience, but at any rate I think you will have seen 

 enough to show you that the first sensation of light is 

 what answers to the violet sensation when it is strong 

 enough to give the sensation of colour. The other sen- 

 sations seem to be engrafted on this one sensation, but 

 in what manner it is somewhat difficult to imagine. 

 Whether the primitive sensation of light was this and the 

 others evolved, of course we cannot know. It appears 

 probable that even in insect life this violet sensation is 

 predominant, or at all events existent. Insects whose 

 food is to be found in flowers seek it in the gloaming, 

 when they are comparatively safe from attack. Prof. 

 Huxley states that the greater number of wild flowers are 

 certainly not red, but more or less of a blue colour. This 

 means that the insect eye has to distinguish these flowers 

 at dusk from the surrounding leaves, which are then of a 

 dismal grey ; a blue flower would be visible to us whilst 

 a red flower would be as black as night. That the insects 

 single out these flowers seems to show that they partici- 

 pate in the same order of visual sensations. I venture to 

 think, without adopting it in its entirety, that these results 

 at all events give an additional probability as to the gene- 

 ral correctness of the Young- Helmholtz theory of colour 

 vision. Where the seat of colour sensation may be is not 

 the point, it is only the question as to what the colour 

 sensations make us feel which the physicist has to deal 

 with. The simpler the theory, the more likely is it to be 

 the true one, and certainly the Young- Helmholtz theory 

 has the advantage over others of simplicity. 



" THE EPIGLOTTIS."^ 



FROM an anthropotomical point of view the epiglottis 

 had for a long time been generally looked upon as 

 a kind of sentinel for the protection of the upper air- 

 passages, when Riickert's comparative anatomical obser- 

 vations showed that the human epiglottis greatly differed 

 from that of mammals, in so far as its relations to the soft 

 palate were entirely altered, and that its physiological 

 cond\i\ons pari passu had undergone important modifica- 

 tions. The new points of view thus obtained induced 

 Gegenbaur to study the comparative anatomy of the 

 epiglottis and its relations to the larynx, and the present 

 volume is the outcome of his investigations. 



The inquiry being undertaken from a morphological 

 point of view the author begins with a study of the differ- 

 ent forms of the epiglottis or epiglottoid structures in low 

 classes of animal life. He next discusses the mammalian 

 epiglottis and its relations to the ^oft palate. The con- 



1 " Die Epiglottis," Vergleichendanatomische Studie, by Carl Gegenbaur, 

 with two plates, &c. (Leipzig : Wilh. Engelmann, 1892.) 



NO. 1223, VOL. 47] 



elusions here arrived at, and which concern the act of 

 deglutition in the lower classes of mammals, lead to a 

 consideration of other organs of the oral cavity, and to 

 an attempt at establishing a connection between these 

 and the apparatus consisting of the epiglottis and soft 

 palate. This in turn induces a minute investigation of 

 the structure of the epiglottis, and of its relationship to 

 the framework of the larynx and the general structure of 

 the respiratory organs in the lowest forms of animal life. 

 In the last chapter the author summarizes the results ob- 

 tained by his comparative studies and throws out such 

 suggestions concerning the origin, development, and 

 function of the epiglottis as would seem justified by his 

 researches. 



Brief as this survey of the course of Gegenbaur's essay 

 necessarily has been, it will be sufficient to show that it is 

 quite impossible to give in the space of a short review a 

 detailed analysis of its contents. Conclusions derived 

 from the synthetic conception of an enormous number of 

 single observations, which extend over a large part of the 

 entire animal kingdom, can only be properly appreciated 

 by a study of the original, and this may be warmly recom- 

 mended. 



The final and most important conclusion arrived at by 

 the author may be briefly summarized as follows : — 



Whilst as high up in the scale as in the sauropsidae, 

 parts of two branchial arches only contribute towards 

 forming the primary hyoid, three more arches are added 

 in the mammals. Two of these growing together form, 

 the transition into the thyroid, which becomes intimately 

 connected with the larynx. 



The mammalian larynx, however, has received a 

 further addition, viz. the epiglottis, the cartilage of which 

 can only be looked upon as the further development of 

 the fourth branchial arch, which in fishes still serves its 

 primitive function, and in the amphibia appears in a rudi- 

 mentary form. The exact manner in which this rudiment 

 passes over into the supporting organ of the epiglottis in 

 mammals is, on the whole, still obscure. So much, how- 

 ever, is certain, that the cartilage of the epiglottis is not a 

 product of mucous membrane, but a genuine part of the 

 skeleton, and that it communicates its supporting 

 function to the whole of the epiglottis, which serves as 

 well the purpose of keeping the air-passages open as of 

 protecting the vestibule of the larynx. 



From this final conclusion it will be seen that, accord- 

 ing to Gegenbaur, the role of the epiglottis in its highest 

 development is purely a respiratory and protective one. 



Pathological observation in man does not admit of 

 these functions of the part being looked upon in any way 

 as indispensable for the existence of the individual. Total 

 loss of the epiglottis has often been observed in various 

 diseases, without the patients either suffering from dysp- 

 noea or from increased liability to the entrance of foreign 

 bodies into the lower air-passages, the constrictor vesti- 

 hiti taryngis {Luschka) in such cases vicariously taking 

 its function. The supposed phonatory role of the epi- 

 glottis, upon which much stress is laid by some eminent 

 singing masters (e.g-. Stockhausen), inasmuch as they 

 maintain that it influences, according to its more erect or 

 more horizontal, position, the "timbre" of the singing 

 voice, is not even mentioned in Gegenbaur's essay. Thus 

 many points connected with this subject still demand 

 elucidation. Still it is impossible to withhold the expres- 

 sion of admiration and of gratitude to the author of the 

 present work for his patient and extensive researches in a 

 very obscure field of comparative anatomy. 



NOTES. 



On Saturday the British Eclipse Expedition to West Africa, 

 arrived safely at Bathurst. The Alecto was there, ready to- 

 convey the party up the Salum River to the selected site. 



