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 



Fio. 24. 



Thenca muricota, Bwk., natural 

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

 polyps (Palythoa). 



sp.h 



L.O: 



Fio. 20. 



FIG. 25. 



Tribrachion Schmidtii, Weltner 

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

 e.t, exhalant tube. 



Disjiringa dinn'miHis, Ridley (after Sollas). A, 

 the whole sponge reconstructed from fragments, 

 i.o, incurrent aperture ; i.t, incurrent tube ; sj).b, 

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

 diagrammatic vertical (longitudinal) section of the 

 sponge. ., b, c, transverse sections at three 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 



