204 Darwin, and after Darwin. 



whether A' and B' are geographically remote from, 

 or close to, A and B ; the point is that, whether in 

 respect of temperature, altitude, moisture, character 

 of soil, &c., there is some difference in the conditions 

 of life experienced by the plants growing at the dif- 

 ferent places. Now, in numberless plants it is found 

 that the typical or constant peculiarities of A' differ 

 more from those of A than they do from those of B ; 

 while, conversely, the characters of A' may bear more 

 resemblance to those of B' than they do to those 

 of A on account of such characters being due to 

 the same external causes in both cases. The conse- 

 quence is that A' might more correctly be classified 

 with B', or vice versa. Another consequence is that 

 whether A and B, or A' and B', be recorded as the 

 "good species" usually depends upon which has 

 happened to have been first described. 



Such a mere abstract of Kerner's general results, 

 however, can give no adequate idea of their cogency : 

 for this arises from the number of species in which 

 specific characters are thus found to change, and even to 

 interchange, with different conditions of life. Thus he 

 gives an amusing parable of an ardent young botanist, 

 Simplicius, who starts on a tour in the Tyrol with 

 the works of the most authoritative systematists to 

 assist him in his study of the flora. The result is 

 that Simplicius becomes so hopelessly bewildered in 

 his attempts at squaring their diagnostic descriptions 

 with the facts of nature, that he can only exclaim 

 in despair " Sonderbare Flora, diese tirolische, in 

 welcher so viele characteristische Pflanzen nur 

 schlechte Arten, oder gar noch schlechter als schlechte 

 Arten, sind." Now, in giving illustrations of this 



