1 



To Doctor Weber in Paris Berlin March 25,1^69 



Most Honored Sir Doctor t 



Höw shall I thank you for the eventful and instructive letter, 

 which you. had the kindness to address to ne on the26th of February and 

 which I received March 13 ? I can only say, that in a long time I did 

 not experience such a gay and happy hour as the one, which gave ne the 

 first reading of your letter, and I hope to to gain pleasure and know - 

 led^e fron it. -In this, it is truly astonishing, how your and my views 

 coincid e IMost of then I can accept without further ad o, and ce^tain 

 items are spoken as fron my own soull To this belonsrs snecially, what 

 you say about the unending variability of most species, which entered 

 your eyes in the sane way as it did mine. If this variability of the 

 Cacti was better knovnr, it could function as a support of Darwin 1 s theo- 

 ry(the Ist edit . of Orisrin of Species by Darwin was in 1859 S.D.). Then f? 

 when I travelled in Mexico, the theorcjes of Darwin were not yet knowrr. 

 but, when his opus appeared later,I found that his views contained a 

 very strong af f irmaticmr through the cactus family. Unf ortunately, the 

 professional botanists are of an entirely different opinion' and the ten- 

 dency of our times does not look toward the conbining of species,, but 1 

 rather the oxmosite, in Splitting then ever more. And this is not only 

 the case in botany; geologists follow the sane direction and truly 

 hor^ible is the confusion for instance in the ornithology, where a 

 slightly slen^rer structure or a slightly different 4 coloration of the 

 plumage is sunposed to be imnediately the basis of a new speciesl - 

 Most striking is the variability of the Stenogoni (ae ? E.D. ) ,and even 

 if one would not want to oonbine the enti-re division into one species, 



^ the different variations could be organized within 4 principle forme. 



^ As such principle formal want to designate E. phyllaoanthus ; E. obvallatus ; 

 !• l^ncif er and E. acif er , E. coptonorronus (Which varles nost strikingly) 

 does probably not belong to the Stenogoni , with which only the flower has 



