The Evolution of Fruits. 11 



order to perpetuate their species. Thus we see such reduction 

 both in the palms and in the oak. 



As an elongated floral receptacle represents a lower type of 

 structure than one horizontally expanded, and this again is 

 earlier than the arrangement by which the ovary appears to 

 be sunk in the receptacle, owing to an absence of separation 

 for some distance between the axial and lateral structures, 

 hypogynous insertion, as it is technically termed, probably 

 preceded perigynous, and perigynous preceded epigynous. 



The comparative anatomy of a group tells us far more as 

 to the structure and evolution of fruits than we can learn 

 from ontogeny, or the study of individual development. All 

 foliar organs originate alike as a mere succulent, cellular 

 papilla; and in vegetable ontogeny stages are so readily 

 masked that whorled carpels seldom show any trace of 

 primitively spiral arrangement, nor can we learn much from 

 their early stages as to the true nature of ovules. Ontogeny 

 is perhaps most useful in discriminating the origin of those 

 layers of the pericarp which are known by the ambiguous 

 terms, epicarp, mesocarp, and endocarp. Probably the 

 carpels of the primitive fruit would so far retain their foliar 

 character as to wither into a dry, parchment-like consistence, 

 and burst by the consequent contraction. Cellular structures 

 in this state are generally slightly hygroscopic, so that we 

 have here the origin of many cases of violent dehiscence 

 facilitating the dispersal of seed. 



If, bearing in mind these general principles, we glance at 

 the distribution of the different varieties of fruits through the 

 natural orders, we are at once struck by the fact that the 

 fruit-type is a character of high phylogenetic importance. 

 The caryopsis of the grasses, the sihcle of crucifers, the 

 hesperidium of the orange tribe, the drupe and the pome in 

 two sections of the EosacecB, the legume of the Leguminosm, 

 the cremocarp of the UmbellifercB, the pepo of the gourd tribe, 

 the cypsele of the Composit(B, and the nut of the CupulifercB, 

 are familiar instances of this. It occurred to me, therefore, 

 to review the natural orders from this stand-point, not 

 disregarding other characters, but paying particular attention 



