SPONGES 



off from one another 



and secondly, the degree to which the indivi- 

 duals produced in this way become 

 distinct from one another, or remain 

 , fused together. 



Instances of the way in which 

 the mode of budding and the union 

 of the persons influence the form 



osc. 



V'' 







FIG. 24. 



Thenea m/iiricata, Bwk., natural 

 size, r.t, root tuft ; p, symbiotic 

 polyps (Palythoa). 



Flo. 25. 



Tribrachion Schmuitii, Weltner 

 (after Sollas). sp.b, sponge body ; 

 e.t, exhalant tube. 



Disyringa dissimilis, Ridley (after Sollas). A, 

 the whole sponge reconstructed from fragments. 

 i.o, incurrent aperture ; i.t, incurrent tube ; sp.b, 

 sponge body ; e.t, exhalant tube ; osc, osculum. B, 

 diagrammatic vertical (longitudinal) section of the 

 sponge, a, b, c, transverse sections at tlflree different 

 points ; a, showing the four divisions of the excur- 

 rent tube; and b, the four divisions of the incurrent 

 tube, which at c is undivided. 



of the colony as a whole are well seen in Ascons, and especi- 

 ally in the genus Leucosolenia, where the individuals can be easily 



