File:Journal of morphology (1892) (14779859541).jpg

Identifier: journalofmorphol1892wist (find matches)
Title: Journal of morphology
Year: 1892 (1890s)
Authors: Wistar Institute of Anatomy and Biology
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Publisher: Philadelphia, Wistar Institute of Anatomy and Biology
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

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has been excludedfrom its just share in forming the conclusions generally acceptedhitherto. The following table gives the genetic relation of the severalsense organs of the ear, the group of animals in which eachorgan made its appearance, the length of time it persisted orwhether it still persists, measured in terms of geological time,the fluctuations undergone by organs during their term of exist-ence, whether of increase or decrease, and the time of deathtogether with the group suffering such loss. In the case ofthe papilla basilaris, although it rises in the Reptilia into the ^ See Recapitulation D. 214 AYERS. (Vol. VI. form of the Sauropsid organ, it is only among the higher mem-bers of the class of Saurians that it is found, while among thebirds the organ is not so fully differentiated as it is in theSaurians, and it is not intended to show by the diagram thatthe Sauropsid organ increases in value or is even present inbirds in such perfection as it exists in the higher Reptilia.
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No. I.) THE VERTEBRATE EAR. 215 Retzius finally came to the conclusion that this nerve endorgan had arisen from the posterior, ampullar sense organ, andthat among the higher forms, especially the Mammalia, it wasno longer produced, or, as he expressed it, the macula neglectain these forms had disappeared in the crista acustica posterior. These canal structures had no special phylogenetic signifi-cance for investigators in this field ; for although it was knownthat the auditory vesicle was invaginated from the surface ofthe body, the connection of the sensory part of the invaginationwith the superficial canal organs was not understood. Nowthat we know that there is a genetic connection, many of theintricate problems receive their solutions, and the genetic rela-tionships appear clear and certain for all the types. Thedemonstration of these facts deals another blow, and a fatalone, at the degeneration hypothesis which has been so persist-ently applied to the elucidation of Cyclostome an

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