PANGENESIS. 171 



in lower and younger forms may be due to the same 

 cause. 



The occasional tendency of hybrids to resemble 

 one parent in one part and the other in another 

 may be due to superabundance of gemmules in the 

 fertilised germ, those from one parent having " some 

 advantage in number, affinity, or vigour over those 

 derived from the other parent." The general pre- 

 ponderance of one parent over the other may be 

 similarly explained. The cases in which " the colour 

 or other characters of either parent tend to appear 

 in stripes or blotches " are to be understood by the 

 gemmules having an affinity for others of the same 

 kind. 



TJie sterility of hybrids is entirely due to the 

 reproductive organs being affected; in the case of 

 plants they continue to propagate freely by buds. The 

 hybrid cells throw off hybrid gemmules which collect 

 in the buds but cannot do so in the reproductive 

 organs. 



Development and metamorphosis. — The remark- 

 able facts of development and metamorphosis are well 

 explained by the hypothesis. Allied forms may pass 

 to a similar end through very dissimilar stages or 

 conversely. Parts may appear to develop within 

 previously existing corresponding parts, or they may 

 appear within parts which are quite distinct. These 

 divergent facts are explained by the hypothesis, 

 each part during each stage being formed inde- 

 pendently from the gemmules of the same part 



