5 



edly correctjonly you should not express yourself , that Q.Dillen Ii 

 be the mexicar form of 0 . Enge l7nan.nl 1 , but rather 0. Endeln which. 

 was onlv described 16 years asro, is the northern form of the long 

 known 0. Dillen.il . I always believed sonethlng like that. And a lot 

 of the newer northern Speeles are with out donbt long-known raexicans, 

 specially in the genus Opuntla ; what I suergested already in part,e.g. 

 0 . Wrightil is O. Kleiniae ; O. arborescens is 0. stell ata etc. 



What you say about the def leient Institution of the "oonni ssl on 

 scientif ique* surprise me ver much. This H Bourjeand M should probably 

 be Bourgean, who tradet in Spain, Afrioa,and last in Northwest Amerika ? 

 If so, then he is a ver industrious and good collector, but obviously 

 not a botanist. What you say about Dera.isne,an old friend of raine,, 

 dumbf ounded. me and made me wonder. I did not expect anything likethis- 

 but, of course, the the pari si an learned in.sti tutions are an evil 

 school . 



Now to your question and your doubts about the genera» The ques- 

 tion is not an easy one for the entire botany and is bei ng answered 

 aecording to different viewpolnts very dif f erently.Thus Benthen and 

 Hooker cortract much in their new works; others multiply the genera 

 indecently - the same as found in the Speeles, I am not satisfaied 

 with the dlvision of the cactl. 



What this qu.es tion concerns, it seems to me the duty of the honest 

 inquirer,to study the groups wh ich offer themsel^es in nature,to 

 rroof their ancestry, to look for dif ferences from other groups, and 

 to weigh the value of these dif ferences, and, then, finally to declde 

 what he wants to join together in <rerus erroupings or must,i.e. what 

 Näture herseif deliniates. But I am forced to again bring to your 

 attention, that unf ortunately most writers about cactiwere not enough 

 botanlsts to be able to distinpruish with a no^e general and f^eer 

 view; must Howe ver still conced, that even n-ood botanlsts have created 



