158 Misce Ua neous. 



The portion of the corpus Bojanl which lines the vascular walls 

 occui-s on the walls of the auriolo, the oblique afferent vein, and 

 the posterior longitudinal vein. This last vessel is only separated 

 from the posterior half of the collecting duct of the corpus Bojanl by 

 a sjiungy lamina or septum of Bojanian tissue, which, being pierced 

 by numerous small orifices, allows of communication between the 

 vessel and the collecting-duct. 



The cells constituting the Bojanian tissue arc not the same 

 throughout. Those of the autonomous portion and of the septum 

 just mentioned are formed of a very transparent protoplasm, in 

 which there are a verj- variable number of small green granules ; 

 they have no nucleus. Those belonging to the walls of the oblique 

 afierent vein and of the auricle contain, besides the green granules, 

 large colourless nuclei provided with one or two colourless nucleoles ; 

 they also contain colourless granules. 



The passage from the cells of the first to those of the second kind 

 takes place rather suddenly, which justifies us in flunking that the 

 latter arc not exclusively Bojanian, but that they may also fulfil 

 other functions. 



The cavity of the pericardium is continuous below, by a passage 

 placed in front of the oblique afferent vein, with the collecting-duct 

 of the corpus Bojani. Between the passage and the collecting-duct 

 there is a narrow oblique orifice which allows the passage of a liquid 

 from the passage into the duct, but impedes its return in the opposite 

 direction. The liquid which has traversed the corjjus Bojani rids 

 itself of certain principles, which are received in the pericardium, the 

 passage, and the collecting-duct. This last C9mmunicates with the 

 exterior by a verj' narrow orifice, placed at the apex of a very small 

 papilla, concealed behind the papillae of the reproductive organs; 

 the discover}- of this orifice is due to M. de Lacaze-Duthiers. The 

 Bojanian coUecting-canal receives in part the blood from the veins of 

 the " bosse de Polichinelle " at the level of the branchial ganglia, and 

 opens posteriorly with a large posterior pallial vein, which serves as 

 a canal of derivation for the blood returning from the mantle at those 

 periods when the pallial circulation is very abundant — that is to say, 

 during the period of reproduction. 



The organs of respiration are multiple. They include the branchiaj, 

 the surface of the body, and especially the inner surface of the mantle 

 and the plaited or frilled organs. 



The branchioe are composed of very small filaments, traversed by 

 a single veiy narrow canal. These branchial canals originate, for 

 the most part, directly from the Bojanian tissue, others fi-om a 

 branchial afterent vessel of spongy or cavernous structure ; they 

 open into an afferent vessel, the diameter of which increases from 

 behind forwards, and which occupies the upper margin of the free 

 lamella of the branchia. This afferent vessel of the branchia receives 

 in front some superficial vessels of the liver, some little veins of the 

 mantle, and the veins of the buccal tentacles, and it opens into the 

 anterior extremitv of the anterior longitudinal vein. The branchial 



