270 LIONEL JAMES PICTON. 



removes, he thinks, waste products from the blood, and stores 

 them up as pigment. The observation from which he draws 

 this conclusion is that pigment is more abundant in the organ 

 in older than in younger individuals. Another function which 

 he suggests it may perform is the secretion of chlorocruorin, 

 the colouring matter of the blood. The embryology of the 

 group is at present unknown ; but the connection which he 

 notes of the heart-body with the wall of the gut, leads Fauvel 

 to conclude that Horst's view of the hypoblastic origin of the 

 organ holds good for the Ampharetidse. He considers, how- 

 ever, that the heart-body may have a different origin in 

 different groups ; that is to say that the heart-body is not 

 homologous throughout the families of Polychaeta in which it 

 occurs. 



In the Ampharetidee, then, Fauvel considers the heart-body 

 as a gland annexed to the digestive tube, and performing a 

 function more or less hepatic. Contrary to Cuenot, he thinks 

 it has no connection with amcebocytes. 



It will be evident from this recapitulation of the history of 

 the subject, that both on the morphology and functions of this 

 curious organ widely divergent views are held. 



In the present paper a description of its anatomy and histo- 

 logy in some of the chief groups in which it occurs will be 

 given, with some observations on the chemical nature of the 

 granules, and on their ultimate fate in connection with the 

 coelomic corpuscles. Matters about which a good account is 

 already existing will be treated briefly. A description of the 

 organ in the Cirratulidse, where it reaches its maximum deve- 

 lopment, will afford the best opportunities for pointing out sig- 

 nificant features which reappear in the different forms. Finally, 

 an account of its principal characters, and of those of the 

 cojlomic fluid, in the Chlorhsemidse, Terebellidee, and Amphic- 

 tenidae, and an instance of its development, will be given. 



Besides in the groups just mentioned, the heart-body occurs 

 also in the Ampharetidse, Spionidse, Magelonidae, and Hermel- 

 lidsB. Its degree of development is very unequal, in Magelo- 

 nidse the organ being merely larval and transitory, whilst in 



