18431862] 



CRUCIFEROUS FLOWERS 



287 



Having nothing on earth to do here, I have dissected all the Letter 615 

 spiral vessels in a flower, and instead of burning my diagrams 

 [figs. 10 and 1 1], I send them to you, you miserable man. But 

 mind, I do not want you to send me a discussion, but just 

 some time to say whether my notions are rubbish, and then 

 burn the diagrams. It seems to me that all parts alternate 

 beautifully by fours, on the hypothesis that two short stamens 

 of outer whorl are aborted ; 1 and this view is perhaps sup- 

 ported by their being so few, only two sub-bundles in the two 



I 



Fig. ii. DISSECTION OF CRUCIFEROUS FLOWER, 



Laid flat open, showing by dotted lines the course of spiral vessels in all the organs; 

 sepals and petals shown on one side alone, with the stamens on one side above 

 with course of vessels indicated, but not prolonged. Near side of pistil with 

 one spiral vessel cut away. 



1 The view given by Darwin is (according to Eichler) that previously 

 held by Knuth, Wydler, Chatin, and others. Eichler himself believes 

 that the flower is dimerous, the four longer stamens being produced 

 by the doubling or splitting of the upper (i.e. antero-posterior) pair of 

 stamens. If this view is correct, and there are good reasons for it, 

 it throws much suspicion on the evidence afforded by the course of 

 vessels, for there is no trace of the common origin of the longer 

 stamens in the diagram (fig. n). Again, if Eichler is right, the four 

 vessels shown in the section of the ovary are misleading. Darwin 

 afterwards gave a doubtful explanation of this, and concluded that the 

 ovary is dimerous. See Letter 616. 



