John Lubbock, Natural History Review: a quarterly journal of biological science (1861)
“ Moreover, although the small attached worm in Sphærularia is not altogether exactly like the ordinary young ones, still, in size and general appearance, it remarkably resembles them; and, lastly, unless we may regard it as being the male, that sex is, as yet, entirely unknown. Although, therefore, I have not been able to distinguish any generative organs, or trace of spermatozoa, I think that I am justified in considering that in Sphærularia the male is far smaller than the female, and that the two are fastened together in a certain definite manner and position. ”
