EXISTENCE BETWEEN BODY-CAVITY AND VASCULAR SYSTEM. 19 



but is surmounted by a number of cells, each with a depression. 

 The fact that it does not open is regarded by Bourne as due to 

 degeneration. This swollen end lies in a space which contains red 

 blood, and there is no sac full of coagulated blood and corpuscles 

 as in Clepsine. 



Nephelis, however, is provided with nephridial funnels which 

 do open on the one hand into the space in which their internal 

 ends are situated, and on the other into a sac similar to that 

 found in Clepsine, which contains both coagulum and corpuscles. 



With regard to the spaces in which the funnels lie, there seems 

 to me to be no doubt that Bourne's description is correct. In 

 Clepsine, the funnels lie in pairs, in the ventral sinus, with the 

 ventral vessel and nerve cord between them. No trace of any 

 special sac, such as is found in Peripatus, is present. 



In Nephelis the funnels open into a special enlargement of the 

 botryoidal tissue, but there is no reason to regard this as anything 

 more than a development of the coelomic spaces, as Bourne has 

 done. 



Again, in Hirudo, where the funnels do not open, the blind 

 internal end lies in a perinephrostomial sinus, which again possesses 

 no characteristics which would justify the assumption that it is 

 fundamentally different from other coelomic spaces. 



Before passing on to consider the means of communication of 

 the vascular and coelomic spaces, I wish to insert a few remarks 

 upon the sacs which are present on the nephridia, which have 

 internal open funnels, and in which numerous corpuscles from the 

 blood are found. These corpuscles seem to be degenerating, and 

 in some cases they appear rather more granular than the normal 

 corpuscles in the blood. 



It has occurred to me that we have to do here with a pheno- 

 menon similar to that which Durham' has described in Asterias 

 rubens. The amoeboid corpuscles, after devouring some substance 

 which it is to the advantage of the organism to excrete, instead of 

 working their own way to the exterior, are taken up by the open 



1 H. E. Durham, " The Emigration of Amoeboid Corpuscles in the Starfish." 

 Proc. Roy. Soc. Vol. 43, p. 327. 



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