M. BATAILLON'S DISCOVERY 219 



— an important fact when considered with the history of 

 the frog's egg and the needle — that " brushing '' the 

 unfertilised eggs of the silkworm and other moths, that is 

 to say, gently polishing the little egg-shells with a soft 

 camel's-hair brush, has the effect of starting development. 

 Taking two lots of unfertilised eggs adhering to slips of 

 paper, as laid by the mother moth, it is found that those 

 gently brushed will hatch, whilst those not brushed will 

 either not hatch at all, or in very small number. The 

 brushing seems to disturb the equilibrium of the proto- 

 plasmic egg-cell within the egg-shell just sufficiently to 

 set it going — going on its course of division and develop- 

 ment. The only other case of " artificially-induced 

 parthenogenesis " at present recorded is that of the 

 common frog, due to M. Bataillon. There are questions 

 of great interest still to be made out as the result of his 

 discovery. Can the fatherless brood be reared to maturity 

 and again made to yield a fatherless generation ? What 

 is the precise structure of the nuclei of the cells which 

 originate from the nucleus of the egg-cell only, and not 

 from a nucleus formed by the fusion of that with a sperm- 

 cell nucleus ? These and similar questions are the motive 

 of further careful study now in progress. 



The important conclusion is forced upon us by these 

 experiments with a needle, that even in so typical and 

 highly organised a creature as one of the higher or five- 

 fingered, air-breathing vertebrates, the egg-cell does not 

 require any material admixture from the sperm-cell in 

 order that it may successfully germinate and develop, but 

 only a disturbance of equilibrium, which can be admini- 

 stered as well by a needle's point as by a sperm-filament ! 

 Yet the whole process of sexual reproduction undoubtedly 

 has, as its origin and explanation, the fusion in the first 

 cell of the new generation from which all the rest will 

 arise, of the material of two distinct individuals. Thus 



