316 Miscellaneous. 



tube accordingly produces and contains a large quantity of poison. 

 The tubes have their common sides united together, and are, in 

 short, deep alveoli. 



Between the tubes we find attached to their walls a number of 

 striated muscular fibres, which are readily distinguishable in well- 

 fixed preparations. These fibres are inserted on the one side by 

 their branching extremities in the excretory duct, on the other they 

 lose themselves in the external tunic of the gland, which is a mus- 

 cular plexus of a similar nature. They exhibit the ordinary trans- 

 verse striation, with alternating thick and thin disks, and a longi- 

 tudinal striation, which shows that they are composed of fibrillse. 

 They have a number of oval granular nuclei, which are ordinarily 

 superficial ; sometimes, however, they occur in the thickness of the 



fibre. 



The external tunic of the gland is nothing but a muscular plexus, 

 the meshes of which are united by a chitinized basal substance. 

 Authors, having seen only the nuclei of the muscles, have described 

 it as an endothelium. This plexus is thick and composed of several 

 layers on the face of the gland opposite to the groove. In the 

 neighbourhood of the groove the fibres are fewer in number and 

 less stout ; they have the same structure as the deep fibres inter- 

 calated between the tubes. 



Thus there is constituted a rich muscular apparatus for the com- 

 pression of the gland and the expulsion of the poison. 



In the other Chilopods the structure is essentially the same. 

 Thus the poison-gland of Cryptops (O. hortensis, Leach) is fairly 

 similar ; but the tubes are more elongated and not perpendicular. 

 There is no groove, and the duct is perforated over the whole of its 

 circumference. The muscles are very greatly developed, especially 

 in the tunic, and are disposed as in the case of Scolopendra. 



The gland of Geoplrilus (G. longicornis, Leach) resembles that of 

 Cryptops. But the muscles of the tunic are no longer plexiform ; 

 they are large fibres as long as the gland, parallel one to another, 

 in a single layer, and fairly similar to all the muscular fibres of the 



° In Lithobius (L. forjlcatus, Linn.) the tunic is a plexus of fibres; 

 their muscular nature, however, is no longer evident. They are 

 fibres which, when treated with acids, prove to be composed of a 

 number of parallel fibrillar, which are devoid of all trace of striation. 

 On their surface are large elliptical nuclei, with a very small 

 nucleolus. Since they resist the action of boiling water and acids, 

 I compare them with the muscular fibres, without believing in their 



contractility. . t- \ 



The structure of the gland in Scutigera (S. coleoptrata, Linn.) 



from a histological point of view is similar to that of Lithobius. 



But the excretory duct remains short, and, since the gland descends 



right into the coxa, the elongation of the poison-claw has here 



occasioned an extreme elongation of the tubes. 



At a future date I shall publish conclusions as to the nature ot 



the poison and its effects.— Comptes Rendus, t. cxix. no. 5 (July 30, 



1894), pp. 352-354. 



