344 DR W. CARMICHAEL M'lNTOSH ON THE STRUCTURE OF THE 



stylets for the central organ. He first indicated, however, the connection between 

 the developing spikes and the clear globules in the lateral sacs, showing that they 

 are sometimes seen in their interior. Finally, he has not discriminated the 

 structure of the reservoir-region, and its relation to the neighbouring parts; and, 

 indeed, his anatomy of the animal, from the limited nature of his observations, is 

 somewhat imperfect. 



M. Claparede,* in his remarks on Tetrastemma taricolor, describes the sac of 

 the central stylet as set in a pale space of a triangular form, and he leaves the 

 stylet-apparatus to hang therein, apparently by its anterior end. He has evi- 

 dently mistaken the translucent wedge-shaped setting of the sac for a cavity, 

 and the triangular muscular structure shown exterior to this has no existence as 

 figured (vide p. 339). He has correctly observed the presence of a duct to the 

 lateral sac, though his figure is somewhat distorted from pressure, and repre- 

 sents the duct by far too wide. He is, moreover, of the opinion that these 

 chambers are not for the sake of furnishing new stylets for the central organ, as 

 Dr Schultze avers, but for the lodgment of those discarded from the latter ; a 

 view quite as erroneous as the other. Each supplies its own stylets. He did not 

 observe any connection between the clear globule in the lateral sacs and the 

 developing spikes. His representation of the muscular fibres of the stjiet-region 

 is faulty. In mentioning the cavity of our reservoir, he properly describes the 

 presence of a liquid containing minute granules in suspension (but not in motion), 

 and that it (reservoir) communicates with the " trompe " by means of an efferent 

 canal : but he fell into the error of regarding the long posterior chamber as a 

 " muscle retracteur." His figure is inaccurate in other respects, such as in the 

 mode of opening of the ejaculatory duct, and in the absence of the muscular space 

 behind the stylet-aperture in the floor of the anterior chamber. He regards the 

 reservoir as a poison-gland, which squirts its contents along the ejaculatory duct 

 into the wounds inflicted by the stylet. This author is scarcely correct in saying 

 that M. de Quateefages had in reality figured this poison-gland without the 

 efferent canal in Polia mandilla; for the French naturalist figures and describes 

 the part as one of the bulgings of his oesophagus, and which, therefore, commu- 

 nicated both with the " trompe " and " intestin." In a still more recent publi- 

 cation! M. Clapaeede exhibits the structure of this region in Keferstein's 

 Prosorliochmiis Claparedii, a viviparous species, but he gives no details of muscular 

 structure. The central stylet and its sac are placed in the middle of a continuous 

 and apparently homogeneous oblong body, the wedge-shaped enclosure of the 

 basal sac and the muscular cavity in front being confounded. The opening of 

 the ejaculatory duct of his poison-gland (reservoir) has the same position as in 

 his previous figure, viz., at some distance from the stylet, and passing directly 



* Recherches Anat. sur les Annelides, Turb. &c. 1861, p. 81, pi. v. fig. 6. 



f Beobach. iiber Anat. und Entwicklung. wirb. Thiere, &c. 1863, p. 23, tab. iv. fig. 10-12. 



