224 



PORIFERA. 



the other or excurrent from the ampullge to the cloaca, the two 

 being connected by the ampullfe ah)ne. Both may consist of lacunar 

 spaces Cfig. 104), or have a more regular arrangement (fig. 165), 





J^ 



\ V," t 



19 



Fig. 16.5.— Section of cortex of ChoudriUanumhi, the skeleton omitted. (After Schulze.) 

 c', afferent canals; c=, efferent canals; y, ampullfe; m, cloaca; o, osculum. 



the canals from the pores uniting in trunks and these in turn 

 branching to go to the ampullaj. The excurrent canals also show 

 a similar tree-like arrangement. Xot infrequently extensive 

 subdermal or subcloacal spaces occur. The relations may be more 

 complicated by the development of several cloacas, or these may be 





1^. 



***, 

 .'*•, 



C5) 



\^. 



'L^ 



Fig. 166. 



Fig. 166.— Surface view of dermal pores of Aplysina ot 

 Fig. 167. — Ascyssa acufera. (.-Vfter Hacckel.) 



Fig. 167. 

 ■ophohin. (After Schulze.) 



repressed; again by tlie branching of the sponge (fig. 107), while 

 still further the branches may anastomose (fig. 108), giving rise to 

 a network. 



Sponges may rei)roduco asexually, small portions separating as 

 bnds and producing noAV animals. Usually sexual reproduction 

 prevails. Eggs and spermatozoa arise from mesoderm cells (fig. 

 \(\;l), are fertilized and undergo segmentation at the point of origin, 

 and leave the parent as fiagellate larvae (fig. lO'.l, A). At fixation 



