PROF. DENDY'S memoir (in Acta Zoologica, 1921, pp. 95-152, 50 figures) on the evolution of the tetraxonid sponge-spicule will appeal equally to those interested in problems of evolution or in ...

1. Modern desmosponge. Find the pores, and notice the thread-like spicules made of protein. This sponge grew up around a bryozoan colony, which you can see at the bottom and top of the specimen, and a ...

To account for the extraordinarily beautiful and varied forms of sponge-spicules, with their wonderful symmetry, has long been one of the most puzzling problems of the zoologist. After more years ...