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Show 496 PROF. G. B. HOWES ON AN UNRECOGNIZED FEATURE [June 7, thyroid cartilage; in the Amphibia, on the other hand, the epiglottidean fold is entirely membranous and in direct connection with the arytenoids, the front faces of which it surmounts (fig. 9, eg.). This difficulty, however, vanishes when it is considered that all recent investigation goes to show that the epiglottis is a secondary structure, formed independently of the rest of the larynx, and subject to the greatest variation. Dubois states1 that in Mammals it represents a chondrification of the submucous tissue of the glosso-laryngeal fold, and that it only secondarily comes into connection with the thyroid cartilage. Clearly, then, the absence of a thyroid cartilage in the Amphibia cannot militate against m y view. The same author further states that the epiglottis is present only in Mammals ; but comparison of figs. 1, 1 a, 4, with His's figures of the human embryo referred to, shows that that is certainly not the case. Consideration of the above facts, taken collectively, forces us to the conclusion that the epiglottis may be represented in Anurous Amphibians, and that in a form most nearly realizing, so far as our present knowledge carries us, the initial stage in its development in man himself. The interest attaching itself to the discovery of the epiglottis in Amphibia is self-evident, and it opens np questions of no little morphological importance. Future investigation must decide how far that which is customarily termed the epiglottis in some Reptiles2 and Birds may or may not correspond with that of Mammals. A consideration of the functional significance of this organ, as here described, reveals some interesting facts. Examination of the figures shows at once that the Amphibian epiglottis cannot have much, if anything, to do with deglutition. The classical Johannes Muller was one of the first to insist3 upon the functional importance of the Mammalian epiglottis as a voice-organ ; and it is now clearly established4 that while that structure is not essential to deglutition, either of solids or liquids, it is indispensable to the full exercise of the voice, playing a part in phonation of unexpected importance. Turning to the Amphibia, it is satisfactory to note that nothing at all comparable to that which I have described is forthcoming among the tailed forms. The epiglottis is clearly appearing among the Anura ; and it becomes a question of the highest interest to inquire, in the knowledge of the above physiological facts, whether its relative development is in any way associated with that of other accessories to the voice, so well known in the males of certain genera. Henle long ago called attention (/. c.) to the existence of minor sexual differences in the laryngotracheal skeleton in Pipa and other Anura. I have already shown that traces of both the epiglottis and epilaryngeal folds may be found in females of certain species (figs. 1 c and 3) ; and, on turning m y attention to the proposition above named, I was, at first, awarded with unexpected success. In a male of 1 L. c. p. 186. 2 Cf. Henle, I. c. pp. 51, 52, and 60, 61. 3 Handbuch d. Pbysiologie, 1840. 4 Walton, " The Function of the Epiglottis," Journ. of Physiology, vol. i. 1878-9. |