2i6 FATHERLESS FROGS 



egg-cell with any matter from the outside ; no paternal 

 " material " is introduced, but the nucleus of the egg-cell 

 divides just as though there had been ! The whole 

 progeny of cells, successively formed, are the pure offspring 

 of the maternal egg-cell and its nucleus. The tadpoles 

 and young frogs so produced are examples of what is 

 called " parthenogenesis " that is to say, virginal reproduc- 

 tion reproduction without fertilisation by material derived 

 from a male parent ! The needle, which gives off no 

 material, but simply makes a tiny break in the surface of 

 the egg, does all that is necessary ! 



To those not acquainted with all that has been ascer- 

 tained as to the reproduction of lower animals, such as 

 insects, crustaceans, and worms, this discovery will appear 

 more astonishing than it really is. We know of many 

 lower animals in which the egg-cells produced by the 

 females do regularly and naturally develop without the 

 intervention of a male and without fertilisation. In an 

 earlier volume^ of this " Easy Chair Series " I wrote of 

 this curious subject, and described the virgin reproduction 

 or parthenogenesis of the hop-louse and other plant lice, 

 of some moths, of some fresh-water shrimps, and of the 

 queen bee (who produces only drones by eggs which are 

 not fertilised). But I had to point out then that no case 

 was known of " parthenogenesis "-that is to say, repro- 

 duction by unfertilised eggs among the whole series of 

 vertebrate animals, the fishes, amphibians, reptiles, birds, 

 and mammals. The chief point of novelty in M. Bataillon's 

 discovery is that we have now an experimental demon- 

 stration of parthenogenesis in a vertebrate animal, and in 

 one so highly organised as the frog. And equally in- 

 teresting, indeed more important from the point of view 

 as to the real meaning and nature of fertilisation, is the 

 mode in which the parthenogenesis of the frog is set 



* Science from an Easy Chair,' Methuen & Co., 1910. 



