Note 469 — Chapter XII · (continued 5)
Reading edition
Notes on Embryology and Classification. Quarterly Journal of Microscopical Science, Vol. XVII. 1877. It seems not impossible, if the speculations in this paper have any foundation that while the views here put forward as to the passage from the Protozoon to the Metazoon condition may hold true for the Spongida, some other mode of passage may have taken place in the case of the other Metazoa.