OCR Text |
Show 1890.] WORMS OF THE GENUS PERICH.ETA. 63 in both specimens (sexually mature) dissected, the probability is that they are definite organs and not temporary outgrowths of the septum caused by its rapid development. The cells covering the septal sacs, when these organs were treated with a weak solution of iodine in potassium iodide, were stained a deep mahogany-brown. This colour disappeared on warming the slide and reappeared on cooling; it seems therefore to be due to the presence of glycogen. Glycogen was first discovered in the tissues of the Earthworms by Claude Bernard, and its presence in that animal has been lately reaffirmed by Barfurth (30). The last-mentioned author particularly states that it occurs in the muscular tissue. As far as concerns the muscles of the septa, I do not find myself able to agree with Barfurth. In preparations of the septal sacs it was distinctly the peritoneal cells and not the muscular tissue which showed the glycogen reaction ; the muscles were stained yellow; and this colour did not disappear on warming, unless the tissue was exposed for some time to a temperature of 60° C , when the colour disappeared hut did not return on cooling. The glycogen reaction was not confined to the peritoneal cells covering the septal sacs, but was found also in the peritoneal cells covering the surface of the septum and elsewhere. The large size of the peritoneal cells upon the septal sacs and their abundant granular contents, combined with their very dark staining, seems, however, to indicate that these cells are specially concerned with the formation of glycogen. The septal gland is so far analogous with the vertebrate liver in that it " has more glycogen than other organs ; it is not an organ sui generis, but only primus inter pares" (Barfurth). The formation of glycogen in the peritoneal cells is interesting, since in the Mollusca the formation of this substance has been shown by Blundstone (31) to occur in the " vesicular connective tissue," which is apparently the lining membrane of the much reduced ccelom of these animals. I may take this opportunity of mentioning that I have found glycogen in the peritoneal cells of AZolosoma, in which worm the presence of glycogen has never yet been recorded. PERICHCETA BISERTALIS, E. P.1 Perichceta biserialis, Perrier, C. R. t. Ixxxi. (1875), p. 1043. Some years ago I received from Manila, through the kindness of Mr. H. E. Barwell, several species of a Perichceta which I refer with some little doubt to the above-named species. M. Perrier has _, as yet only given a very short preliminary account of this species, which cannot be regarded as sufficiently defined. The most marked external characters are the peculiar ventral 1 M . Vaillant (23 A ) proposes subgeneric rank for this species under the name of Pcrriera, on the grounds that there is a median and ventral line devoid of seta?. P. luzonica is referred to the same subgenus. I have already (53) discussed this question ; but these species are not the only two with ventral gaps. |