HEART-BODY, ETC., OF CERTAIN POLYCH^TA. 295 



The futictioii of chloragogen is a much-debated question. 

 Certain text-books speak of the tissue frankly as " liver cells.'' 

 Schneider suras up the facts which point to such a conclusion : 

 " Den Leberzellen ahneln die Chloragogenzellen in folgenden 

 Punkten. Sie nehmen Pigmente (Kiikenthal) und albuminoide 

 Substanzen (Cueuot) wahrscheinlich aus dem Blut auf und 

 absorbiren Indigkarrain und Eiseu aus injicirten Losungen "" 

 (30j A, p. 386). The analogy with the liver of Vertebrates 

 is emphasised when the chloragogen is in the form of a 

 heart-body; it is then situated in the stream of blood from 

 the alimentary to the respiratory organs — in the portal blood, 

 in fact ; and it is reasonable to conclude that its functions 

 play a similar part in the economy of the worm to that under- 

 taken by the liver in as far as the latter may be regarded as a 

 ductless gland. 



The analogy cannot be followed into details. Glycogen, 

 though occurring in Sipunculus (Jourdan), and described even 

 in the chloragogen of Oligocheeta (Cuenot, 1897), appears to 

 be absent in the heart-body. Other substances, however, may 

 exist in it, representing elaborated and stored products. Fat 

 and iron have been shown to be present, and the latter, it can 

 hardly be doubted, is associated with the haematopoietic func- 

 tion. The functions of the pigment and the chitinous bodies 

 are obscure, and if they be excretory their mode of removal is 

 difficult to understand. It has been suggested above that 

 waste products may be carried through the heart wall, and 

 thence to the nephridia by leucocytes, or emptied into the 

 blood and removed by gill excretion ; the latter alternative 

 seems only applicable to fluid substances. 



With regard to the mechanical functions of the heart-body 

 wc are on surer ground. The vessel wall contracting upon it 

 obliterates the heart cavity at systole, the whole of the blood 

 passing on to the gills. 



In conclusion I wish to offer my sincere thanks for the 

 assistance I have received from the Staff of the Zoological 

 Station at Naples. Professor Paul Mayer gave me invaluable 



