SEA-FISHERIES LABORATORY. 415 



are probably dissolved in the lymph. The cells them- 

 selves are eaten by the young clear amoebocytes, which 

 thus act as phagocytes. The phagocytic function is 

 limited to the young cells only. After the appearance 

 of the eosinophilous granules they cease to act as 

 phagocytes. 



Cuenot* claims also to have discovered a phagocytic 

 gland which is quite distinct from the lymphatic gland. 

 It is a swollen mass of cells situated on the terminal 

 branches of the hepatic artery. The cells resemble the 

 free amoebocytes and probably act as phagocytes. 



When the blood ceases to flow, coagulation takes 

 place. This is effected by the clear amoebocytes. These 

 cells become changed in their appearance, and they send 

 out numerous fine pseudopodia which unite with those of 

 the neighbouring cells to form a network, in which all 

 the cells are united together. Thus a clot is formed. 



The " Pericardial Pouch." 



At each of the postero-lateral corners of the peri- 

 cardium there is a structure which Cuenott designated 

 the " poche pericardiale." In Cancer each pouch lies on 

 the upper part of the posterior thoracic epimera and pro- 

 jects into the branchial chamber. Externally, each pouch 

 is covered with a cuticle which is continuous with the 

 chitinous wall of the branchial chamber. The cavity of 

 the pouch, which is continuous with the pericardial sinus, 

 is to some extent broken up by connective tissue cells 

 and by muscle fibres. The function of these pouches is 

 unknown. 



* Cuenot, L. Comptes Rendus, 1903 (No. 137), p. 619. 

 f Cuenot, L. " fitudes physiologiques sur les Crustaces 

 Decapodes." Archives de Biologie, t. XIII (1895). 



