Diagram showing the Ascon type of sponge. ec., ectoderm; r.c., radiating canals; i.p., internal pores;…
"Diagrams to illustrate the development of one of the simpler types of sponge: I, the egg; 2, section…
"Vertical section of a fresh-water sponge (Spongilla), showing the arrangement of the canal-system.…
"Transverse section through the wall of a cylinder (parallel with the course of the canals), showing…
Diagram showing the Sycon type of sponge. ec., ectoderm; r.c., radiating canals; i.p., internal pores;…