| OCR Text |
Show 1885.] DR. HUBRECHT ON A NEW PKNN ATULID. 515 exterior. This expansion, which was characterized by its more brownish-yellow colour from the rest of the red polyparium, is now seen to owe this different coloration to the absence of spicules in this part; the spicules are seen to diminish in size in the vicinity of the disk (fig. 9), several of them being yet imbedded in its circumference, but none in its central portion. The gradual passage of this sclerenchymatous tissue into the rest of the investment of the polyparium is more clearly visible in the adjacent longitudinal section. It may be further gathered from the figures 10 & 11, the former figure at the same time serving to demonstrate both the directions in which the spiculee are placed in the wall of the stem, and the more or less complicated trabecular arrangement of the sclerenchyma, as it is found inside the outer spicule-bearing layer and surrounding the spaces in the stem. I have, finally, to mention numerous pores by which the walls of Figs. 1-3. Echinoptilum macintoshii. 1. Transverse section of lower part of stem. 2. Ditto of upper part of stem. 3. Ditto of rhachis. Fig. 4. Cavernularia liitkenii. transverse section of lower part of rhachis (after Kolliker, I. c. pi. 23) ; a, axis. the polyparium are perforated, and which in transverse sections are found to correspond to the small zooids. From this it follows, and the sections moreover entirely corroborate the conclusions, that these pores are more numerous on the dorsal surface (cf fig. 6) than elsewhere. One of these pores is represented magnified and in transverse section in fig. 8. Remains of polyps could in m y specimen not be detected in the cavities into which these pores lead ; still from analogy I feel justified in calling the external small polyp-cells corresponding to these openings, zooids. After having tht. s given our attention to the external and internal characters of the polyparium, we should have to examine the soft tissues, the polyps themselves, the reproductive apparatus, &c. Unfortunately the one specimen I felt justified in dissecting has hardly anything to teach us in that respect. The remnants of the polyps extruding from their polyp-cells were well visible even with a hand-glass, upon superficial examination of the specimen, and even a number of long tentacles could be seen to belong to each of the polyps. They had, however, so flat and shrivelled an appearance that I was doubtful whether they would give any histological information when section-ized. M y doubts were realized, and I have come to the conclusion that since 1874, when the polyparia were captured, they must have gone through a phase of desiccation, although when I received them |
