[456] “A contribution to the history of the development in the Guinea-pig,” Journal of Anat. and Phys. Vol. XI. pp. 332-336.
[457] The spaces between the layers in these sections are due to the action of the hardening reagent.
XV. On Certain Points in the Anatomy of Peripatus Capensis[458].
The discovery by Mr Moseley[459] of a tracheal system in Peripatus must be reckoned as one of the most interesting results obtained by the naturalists of the “Challenger.” The discovery clearly proves that the genus Peripatus, which is widely distributed over the globe, is the persisting remnant of what was probably a large group of forms, from which the present tracheate Arthropoda are descended.
The affinities of Peripatus render any further light on its anatomy a matter of some interest; and through the kindness of Mr Moseley I have had an opportunity of making investigations on some well preserved examples of Peripatus capensis, a few of the results of which I propose to lay before the Society.
I shall confine my observations to three organs. (1) The segmental organs, (2) the nervous system, (3) the so-called fat bodies of Mr Moseley.
In all the segments of the body, with the exception of the first two or three postoral ones, there are present glandular bodies, apparently equivalent to the segmental organs of Annelids.
These organs have not completely escaped the attention of previous observers. The anterior of them were noticed by Grube[460], but their relations were not made out. By Saenger[461], as I gather from Leuckart's Bericht for the years 1868-9, these structures were also noticed, and they were interpreted as segmental organs. Their external openings were correctly identified. They are not mentioned by Moseley, and no notice of them is to be found in the text-books. The observations of Grube and Saenger seem, in fact, to have been completely forgotten.
The organs are placed at the bases of the feet in two lateral divisions of the body-cavity shut off from the main central median division of the body-cavity by longitudinal septa of transverse muscles.