and Physiology of the Spongida. 



23 



tube somewhat inflated at its extremity, where the neck of the 

 inflation is surrounded by a sarcodic frill ; and from its summit 

 proceeds a long cilium (altogether not unlike the pistil and 

 corolla of a flower), while in the body may be observed a 

 granuliferous sarcode containing a nuclear organ and one or 

 two "contracting vesicles," which, carrying out the simile, 

 would be analogous to the seed-vessel of the flower. 



Fisr. 1. 



Fig. 2. 



Fig. 1. Common form of spongozoon in Grantia compressa. 



Fig. 2. Not unfrequent form : a, body ; b, nucleus; c c, contracting' vesicles ; 



d, granules of sarcode ; e, grains of food ; f, rostrum ;; g, collar ; 



h, cilium. 



Scale l-4tk to l-6000th of an inch. 



The conical bulb-like portion has been called the " body ;" 

 the bacilliform tube, the "rostrum" or beak ; the sarcodic frill, 

 the "collar," in the midst of which is the inflated end of the 

 rostrum and the cilium. 



This, then, is the form of the spongozoon of Grantia com- 

 pressa in its active living state ; and that it is the animal of 

 the sponge may be assumed from no other body or cell in 

 the sponge taking in the colouring-matter *. 



That the particles of colouring-matter pass into the ampul- 

 laceous sac directly through the pore has been demonstrated 

 by the presence of a continuous line of colouring-matter having 

 been seen to exist between the pore on the surface and the 

 ampullaceous sac ('Annals,' 1874, vol. xiii. p. 437) ; and that 

 subsequently it may pass into the body of the spongozoon 

 through the rostrum or beak (by the side of the cilium, as 

 in such flagellated Infusoria generally) seems most probable, 



* It must not be thought that the colouring-matter requires to be so 

 minutely divided as for its particles to be almost imperceptible, since the 

 " rostrum " is so expansible that it will often admit the spores of Algje 

 into the " body " of the spongozoon, especially at tlie end of the breeding- 

 season (say June), when the form of the spongozoon generally also appears 

 to be best developed. 



