1890.] WORMS OF THE GENUS PERICH^TA. 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 Bar- 

 furth. In preparations of the septal sacs it was distinctly the 

 peritoneal cells and not the luuscular tissue which showed the 

 glycogen reaction ; the muscles were stained yelloiv ; and this 

 colour did not disappear on warming, unless the tissue was exposed 

 for some time to a temperature of G0° C, when the colour disappeared 

 but did not return on ccoliiig. 



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 tlie 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 pritims 

 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 JEolosoma, in which worm the 

 presence of glycogen has never yet been recorded. 



Perich^ta biserialis, E. P.^ 



PerichcBta 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 tiiis species, 

 which cannot be regarded as sufficiently defined. 



The most marked external characters are the peculiar ventral 



^ M. Vaillant (23 a) proposes subgeneric rank for this species under the 

 name of Perriera, on the grounds that there is a median and ventral line devoid 

 of setse. P. luzonica is referred to the same subgenus. I have already (53) 

 discussed this question ; but these species ai-e noi the only two with ventral gaps. 



