200 Miscellaneous. 



the sections the capsule is seen to be divided iuto distinct lobes, 

 pressed one against the other, showing that it is formed by a rolled- 

 up canal, the walls of which have fused. 



The canalicular chain corresponds with the region which German 

 naturalists have named " 8chleipenorgan " in the excretory apparatus 

 of the Hirudinete. It is traversed throughout its whole length by 

 four canals, which communicate two and two, at its free extremity. 

 This caused Lemoine (1880) to believe that it is formed by two 

 pairs of united canals. In reality the direction of the current indi- 

 cated by the tlagella in the iuterior of these canals, as well as their 

 relation to the canalicular structures of the capsule, oblige us to 

 consider the " Schlei pen organ " as a single and distinct canal. After 

 taking its origin in the lacunar system of the capsule, it is folded 

 four times on itself, its faces of contact are fused together, and is 

 continued into the excretory canal. 



The communication one with another of these supposed four 

 canals, as well as the continuation of the " Schleipenorgan " into the 

 excretory canal, takes place in the capsule. Contrary to the asser- 

 tions of the authorities previously cited, the internal cavity of the 

 excretory canal is completely bare of vibratile cilia and flagella. 



The terminal vesicle, oval in form, opens directly on the exterior 

 by the excretory orifice ; it has a longitudinal diameter of 80-90 ^ 

 in a state of extension. It is formed by an invagination of the 

 integument. Its wall is made up of three successive layers, which 

 are, from within out, an epithelial coat, clothed by a cuticle which 

 represents the ectoderm ; a middle muscular coat, formed by the 

 circular fibres of the body-wall ; and a delicate external membrane. 

 There are no vibratile cilia in the interior. 



The excretory apparatus of Branchiohdella has the same structure 

 as the corresponding apparatus in the Hirudiuese, and appears to be 

 of an intracellular character ; the protoplasm presents around the 

 cavities well-marked radial striations. Tlie nuclei are distributed 

 in its interior, but no limiting membrane of the cellular masses 

 exists. 



The whole surface of the nephridium is enveloped in the peri- 

 toneum, which constitutes ligaments and exhibits in certain places 

 large granular peritoneal cells. 



I have made no direct experiments to determine the physiological 

 role of the nephridia of Branchiohdella (1 propose to attack this 

 question shortly), but observations made upon the living animal 

 enable me to assert that, besides liquid excreta, these organs absorb 

 solid matters. These latter arise from the breaking down of the 

 chloragogenic cells, detached from the intestine, and of too large a 

 size to penetrate into the vibratile funnel. I have never seen solid 

 bodies in the interior of the " Schleipenorgan " nor in the terminal 

 vesicle. The solid particles which have penetrated through the 

 funnel are stopped in the capsular lacunge, where probably they are 

 destroyed. It is possible that the accumulation of pigment in the 

 cellular mass, which I have described, in the capsule arises from this 

 destruction. — Comftes llcndus^ 1896, t. cxxii. pp. 1069-1071. 



