378 PROVISIONAL HYPOIHESIS Chap. XXVII. 



A feather, for instance, is a complex structure, and, as each 

 separate part is liable to inherited variations, I conclude that 

 each feather generates a large number of gemmules ; but it 

 is possible that these may be aggregated into a compound 

 gemmule. The same remark applies to the petals of flowers, 

 which are sometimes highly complex structures, with each 

 ridge and hollow contrived for a special purpose, so that 

 each part must have been separately modified, and the 

 modifications transmitted; consequently, separate gemmules, 

 according to our h^'pothesis, must have been thrown oif from 

 each cell or unit. But, as we sometimes see half an anther 

 or a small portion of a filament becoming petali-form, or parts 

 or mere stripes of the calyx assuming the colour and texture 

 of the corolla, it is probable that with petals the gemmules 

 of each cell are not aggregated together into a compound 

 gemmule, but are free and separate. Even in so simple a 

 case as that of a perfect cell, with its protoplasmic contents, 

 nucleus, nucleolus, and walls, we do not know whether or 

 not its development depends on a compound gemmule derived 

 from each part.^^ 



Having now endeavoured to show that the several fore- 

 going assumptions are to a certain extent supported by analo- 

 gous facts, and having alluded to some of the most doubtful 

 points, w^e will consider how far the hypothesis brings under 

 a single point of view the various cases enumerated in the 

 First Part. All the forms of reproduction graduate into one 

 another and agree in their product; for it is impossible to 

 distinguish betw^een organisms produced from buds, from self- 

 division, or from fertilised germs ; such organisms are liable to 

 variations of the same nature and to reversions of the same 

 kind ; and as, according to our hypothesis, all the forms of re- 

 production depend on the aggregation of gemmules derived 

 from the whole body, we can understand this remarkable 

 agreement. Parthenogenesis is no longer wonderful, and if 

 we did not know that great good followed from the union of 

 the sexual elements derived from two distinct indi^dduals, the 



** See some good eriticisnis on this Lewos in the 'Fortnightly Review,' 

 head hy Delpino, and by Mr. G. H. Kov. 1, 1868, p. 509. 



