OCR Text |
Show 830 MR. F. E. BEDDARD ON [Nov. 3, of this epithelium is displayed in Plate LII. fig. 6. The columnar cells are still present and of the same general appearance, but between them are a number of large, oval, granular cells (a), which are considerably shorter and do not reach the surface ; towards the external aperture of the pouch the granular cells disappear, and the epithelium gradually passes into the outer epidermis without any distinct break. These changes in the structure of the copulatory pouch are accompanied by changes in the structure of its diverticula Before describing these, I should mention that the copulatory pouches were invariably empty of spermatozoa ; in no case did I find the least traces of spermatozoa in the copulatory pouch itself; on the other hand, the diverticula were as invariably full of spermatozoa compacted together in a way that will now be described. In the first-mentioned individual, in which the copulatory pouches present the more simple structure, the accessory pouches are also comparatively simple in their structure. The epithelium consists of tall columnar nucleated cells, quite similar to those which form the inner lining of the copulatory pouch ; the epithelial layer is thrown into folds, and in the distal portion of the chamber these folds meet and divide the cavity into a number of smaller cavities ; of the copulatory pouch itself, on the other hand, the cavity is never thus subdivided. Here and there the epithelial cells are replaced by largish oval spaces, apparently filled with a fluid substance, and which are probably due to the degeneration of cells ; in many of these were imbedded packets of spermatozoa arranged in longitudinal bundles and closely cemented together. In the more mature individual the structure of the diverticula was almost completely lost: it appeared to form a completely solid mass, without any trace of a lumen or only just the faintest trace near to its external aperture. The interior of the pouch consists of masses of granular matter of various sizes and shapes (see Plate LIU. figs. 10 and 11), in which were imbedded bundles of spermatozoa ; trabeculae of a tissue, which may represent the degenerated epithelium, form a complete network, and separate off from each other the granular masses containing the spermatozoa. This condition is obviously brought about by a still further activity of the epithelium of the diverticula, of which there were indications in the first stage. It appears to me therefore that in this species the copulatory pouch itself has little or no share in the phenomena of reproduction ; the spermatozoa, perhaps cemented together in bundles by the secretion of the prostate glands, are transferred direct to the diverticula of the copulatory pouches, where they undergo further change, which perhaps results in the formation of a spermatophore ; I have not, however, succeeded in finding any spermatophores. The main fact to which I wish to call attention, is that the diverticula of the copulatory pouch, and not the pouch itself, have the chief share in the process of fecundation. In A. nova zelandia I am not able to give any details of the |