MR. R. GURNEY ON THE LIFE HISTORY OF THE CLADOCERA. 45 
to reproduce without the need of males were hermaphrodite, 
even though male organs could not definitely be seen. 
Schaeffer (1755), Ramdohr (1805), and Strauss (1819), for 
example, supposed that they were capable of self fertilisation. 
Parthenogenesis as a mode of sexual reproduction was not 
fully proved to exist till 1845, when it was shown by Dzierzon 
that the Honey Bee produces eggs which develop either with 
or without fertilisation. Hitherto, when it had been shown 
that, as in the case of Aphis, egg-like bodies might give rise 
to young without fertilisation, it was assumed that these 
