260 ORIGIN OF CULTIVATED PLANTS. 



mens, attributes only G. turbinatus to tngonus. The 

 specific difference between G. Melo and G. trigonus is 

 unfortunately obscure, from the characters given by 

 these three authors The principal difference is that 

 G. Melo is an annual, the other perennial, but this dura- 

 tion does not appear to be very constant. Mr. Clarke 

 says himself that G. Melo is perhaps derived by cultiva- 

 tion from G. trigonus ; that is to say, according to him, 

 from the forms which Naudin attributes to G. Melo. 



The experiments made during three consecutive years 

 by Naudin^ upon the products of Giuiv/mis trigonus, 

 fertilized by G. Melo, seem in favour of the opinion which 

 admits a specific diversity ; for if fertilization took place 

 the products were of different forms, and often reverted 

 to one or other of the original parents. 



2. The African forms. Naudin had no specimens in 

 sufficiently good condition, or of which the wild state 

 was sufficiently certain to assert positively the habitation 

 of the species in Africa. He admits it with hesitation. 

 He includes in the species cultivated forms, or other wild 

 ones, of which he had not seen the fruit. Sir Joseph 

 Hooker ^ subsequently obtained specimens which prove 

 more. I am not speaking of those from the Nile Valley,^ 

 which are probably cultivated, but of plants gathered by 

 Barter in Guinea in the sands on the banks of the Niger. 

 Thonning * had previously found, in sandy soil in Guinea, 

 a Gucwmis to which he had given the name arenarius ; 

 and Cogniaux,^ after having seen a specimen brought 

 home by this traveller, had classed it with G. Melo, as 

 Sir J. Hooker thought. The negroes eat the fruit of the 

 plant found by Barter. The smell is that of a fresh green 

 melon. In Thonning's plant the fruit is ovoid, the size 

 of a plum. Thus in Africa as in India the species bears 

 ymall fruit in a wild state, as we might expect. The 

 Dudaim among cultivated varieties is allied to it. 



• Naudin, Arm. Sc. Nat., 4th eeries, voL xviii. p. 171. 



• Hooker, in Oliver, Fl. of Trap. A/r., ii. p. 546. 



» Schweinfurth and Ascherson, Aufz&hhmg, p. 267. 



• Schumacher and Thonning, Guineishe Planten., p. 426. 

 ' Cogniaux, in de CandoUe, Monogr. Phxmir., p. 483. 



