454 MB. C. DAKWIN OS SPECIFIC DIFFEHEiN^CES IX PRIMrLA. 



feriiig much from each other ; for hybrids of the first generation, 

 when raised from uncultivated plants, are generally uniform in 



character. 



first 



we may safely conclude, from the absolute sterility of all those 

 observed by me in a state of nature, and of the one plant in my 

 garden, excepting when artificially and repeatedly fertilized with 

 pure pollen ; and then the number of seeds produced was extremely 

 small. From these hybrids varying so much, an almost perfect 

 series of forms connecting the two parent species, though these 

 are widely distinct, could easily have been selected. This case, 

 like that of the common Oxlip, shows that botanists ought to be 

 cautious in inferring the specific identity of tAVo forms from the 

 presence of intermediate gradations ; nor in the many cases in 

 which hybrids are moderately fertile would it be easy to detect a 

 slight degree of sterility in plants growing in a state of nature and 

 liable to be fertilized by either parent species. Thirdly and lastly, 

 these hybrids ofier an excellent illustration of one of the many 

 profound remarks made by that admirable observer Gartner, 

 namely, that although plants which can be crossed with ease ge- 

 nerally produce moderately fertile offspring, yet well-pronounced 

 exceptions to the rule occur ; and here we have species of Verhas- 

 cum which are evidently crossed with the greatest ease, but pro- 

 duce hybrids which are excessively sterile. 



