238 M. Ch. Naudin on Hyhridity in Plants. 



ber of individuals, and always faithfully reproduced in every 

 generation. 



But it is more than probable that in a multitude of cases 

 (in the genus Buhus, for example) purely individual varia- 

 tions without persistence, have been taken for common 

 characters, constant and transmissible. 



Does it then follow that the terms race and variety ought 

 to be banished from the science ? Certainly not, for they 

 are convenient to designate weak species that ought not 

 to be enrolled among the official species, but it is proper 

 to give them their true signification, which is absolutely 

 the same as that of species properly so-called, and to see in 

 forms designated by these terms some unity of a weak kind, 

 which might be neglected without inconvenience to the 

 science. 



9. Can Artificial Hybridisation furnish a mark to determine what 

 it is proper to distinguish as Species P 



I have not the least doubt but that there are some cases 

 where it would be of a slight assistance, and again a greater 

 number where it would not be practicable. Here are some 

 examples of its practical utility. 



I have stated before, in speaking of the three species of 

 eatable gourds, that they but slightly differ in outward ap- 

 pearance, and even by their intimate characters, for most 

 botanists cannot clearly distinguish them; Linnaeus himself 

 confounded them in one. But these three plants refuse to 

 give hybrids by mutual crossing ; they are then three self- 

 governed species perfectly distinct. 



M. Dunal, in his Monograph of Solanacese, combines into 

 one species Datura Stramonium and D. Tatida, considering 

 them as simple varieties of the same species. But the pro- 

 duce of their crossing does not vegetate altogether like 

 these two forms ; it grows much larger and flowers less, 

 inasmuch as it loses its flower-buds in the seven or eight 

 first branches. This disturbance caused in the vegetation 

 of the mixed produce, is an indubitable sign of a difference 

 in the autonomy of the two parent forms ; therefore these 

 forms ought to be held as distinct species. 



