486 Mr. A. T. Masterman on the Nutritive and 



the first series fifteen seconds after being removed from the 

 carmine solution tlie choanocytes are all well charged with 

 particles. A minute examination brings to light just a few 

 particles here and there in the endodermal pinnacocytes, 

 which are, at any rate, sufficient to show that these cells are 

 at least capable of absorbing substances, tliough there are too 

 few to allow us to assign a digestive function to them. 



Fier. 1. 



Transverse section of Grantia, showing loaded choanocytes. 



There can be no doubt that in Grantia at least the choano- 

 cytes form the active ingestive tissues. 



In all the series up to about three or four minutes the 

 choanocytes still have carmine in their substance, but later 

 than this they gradually lose it, until as late as ten or 

 twelve minutes they are practically free of all particles. 

 Amongst the charged choanocytes we notice that here and 

 there are cells which have commenced to lose the defi- 

 nite cell-outline which distinguishes the normal choanocyte, 

 and, later, to lose their flagella. Stages in this process of 

 phagocytic degeneration can be observed, and although at 

 first cells undergoing this change are scattered here and there 

 in the endodermal chambers, yet in some of the series there 

 are whole chambers which have been reduced by this process 

 to the state of an amoeboid multicellular mass, in which the 

 only indication of the former cellular condition is the row of 

 cell-nuclei dotted about in its substance. 



Such an appearance is shown in figure 2 i, where the 

 amoeboid mass is scon to be in direct protoplasmic connexion 

 with the mesodermal elements ; and there is every reason to 

 interpret this appearance as a wandering inwards o( the 

 transformed choanocytes. In fig. 2 a is seen an endodermal 

 chamber in which some of the cells have not reached so 



