Miscellaneous. 315 



The Poison-Gland of Chilopod Myriapoda. 

 By M. 0. DuBoscQ. 



In spite of the recent investigations of MacLeod, Soulie, Zograf, 

 and Herbst, the poison-gland of Chilopod Myriapods is not well 

 understood. We know that in all Chilopods the orifice is situated 

 on the buccal side of the tip of the fang, that this orifice is succeeded 

 by a tubular chitinous duct which extends as far as the coxa of the 

 poison-claw, and that around the duct a tissue of a nacreous white 

 constitutes the gland, which has a cylindrical shape in Scolopendra, 

 but is piriform in the rest of the Chilopoda. But as to the actual 

 structure of the glandular tissue authors are entirely at variance. 

 Some (MacLeod, Herbst) describe around the duct large radiating 

 cells, which are said to have a nucleus at the base. Their opponents 

 (Soulie, Zograf) regard these pretended cells as glandular tubes with 

 multiple secreting cells. As for the muscles of the gland, since no 

 one has seen any sign of such structures, all suppose that the gland 

 is compressed by the adductor muscles of the poison-claws, the 

 result of which, however, would be to cause the poison to issue at 

 each movement of these foot-jaws. 



According to my own researches the structure of the gland in 

 Scolopendra (Sc. cingulata, Latreille) is as follows : — 



The excretory duct, which consists of very thick chitin, is divided 

 into two portions, an anterior one, which is non-glandular and 

 presents no peculiarity except more or less parallel thickenings, 

 giving it a faint resemblance to a trachea ; and a posterior glandular 

 portion, of the same thickness and the same calibre, but pierced with 

 olive-shaped foramina. These foramina have been taken by many 

 to be little hollow protuberances attached around the excretory 

 duct ; this is due to the fact that the lining chitin is denser than 

 the uniting chitin, which is pale, whence the appearance of relief. 

 They do not occupy the whole of the surface of the posterior portion, 

 but only three fourths of it. The external region, to which the 

 groove of the gland corresponds, is destitute of them throughout its 

 length. 



The glandular tissue seems to be disposed all round the excretory 

 duct, which apparently has a central position. In reality the duct 

 is superficial, since it is at the bottom of a longitudinal groove in 

 which ramify the tracheae and the arteries of the gland. (The 

 nerves of the gland, derived from the nerve of the poison-claw, 

 spread out on the side opposite to the groove.) At the bottom of 

 the groove the chitin of the duct is not bare, but is clothed with a 

 columnar epithelium. 



Around the duct and perpendicular to it there radiate a number 

 of glandular tubes, one of which inosculates with each foramen in 

 the duct. Each tube is conical or pyramidal in shape, with the 

 foramen in the duct as the apex of the cone. Their walls are con- 

 stituted by a delicate basal membrane, slightly chitinized, in which 

 we observe granular oval nuclei at intervals. The base alone is 

 occupied by little gland-cells, engaged in active proliferation. Each 



