312 BIOLOGY, [BOOK iv. 



" Nature tells us in the most evident manner that she has horror 

 of a perpetual atitofecundation." 



The female ovulum can be fecundated at various moments of 

 its evolution, at various degrees of maturity, and it is probable 

 that the epoch of fecundation has an influence on the future 

 direction of this evolution, which has not an immutable character. 

 "We shall see in effect, further on, that disturbing causes, even 

 though slight, acting on the fecundated ovum, can make the 

 embryonary development vary in a very large measure. That 

 even the production of the one sex or the other may be connected 

 with the degree of maturity of the fecundated ovulum is not, a 

 priori, an inadmissible supposition. 



Girou de Buzareingues demonstrated in the female slips of 

 phanerogamous dioic plants with the flowers in clusters, that the 

 male or pollinical cells, when they fell on the whole cluster and 

 fecundated all the flowers thereof, produced very various results 

 according to the degree of maturity of the ovula. At the lower 

 part of the cluster, where the most advanced flowers are found, 

 the fructification gave male seeds, while the flowers less ripe, 

 those at the top of the cluster, produced female seeds. 



Starting from this idea, and supposing that the complete 

 maturity of a female ovulum might be very favourable to the 

 production of the male sex, and inversely, M. Thury, of Geneva 

 (1863), caused cows to be impregnated, sometimes at the com- 

 mencement, sometimes at the end, of the rutting period. In the 

 first case he obtained female calves ; in the second, male calves. 

 The experiment was recommenced by a Swiss agriculturist, M. 

 Cornay, who, twenty-nine times in twenty-nine cases, succeeded 

 in producing at will such or such a sex. 1 These are positive facts 

 which are not weakened in any considerable degree by contra- 

 dictory observations, almost all susceptible of different inter- 

 pretations ; and assuredly the question deserves to be taken up 

 afresh and seriously studied. 



In the preceding fact an observation made on ovular develop- 

 1 Cl. Bernard, loc. tit. 



