STRUCTURE OF FLOWERS. 125 



ordinary pistil, in such a manner as to form a kind of 

 sheath, so as to present on a transverse section, besides 

 the two central cells, as many others in an outer row as 

 there were anthers converted into cai-pels. The same 

 fact was observed by Roeper in Campanula Rapuncu- 

 loides, the fruit of which was found to present two rows 

 of carpels. It is not improbable but the small number 

 of cases where fruits with two rows of seminiferous cells 

 have been described may be phenomena of this class. 



Another change, more rare than the preceding, is 

 that where a carpel is changed into a stamen : Roeper 

 has observed it in Euphorbia palustris and Gentiana 

 campestris. In these cases one of the carpels seemed 

 wanting, and was found under the form of an anther. 

 Not having had an opportunity of seeing this phenome- 

 non myself, I cannot describe it in detail. It is likely 

 that in several dioecious plants we might find that 

 the central stamens of the male flowers are carpels meta- 

 morphosed. Perhaps, also, in some flowers which have 

 an inner row of incomplete stamens, and the number of 

 carpels less than in the normal state, it might be found 

 that these incomplete stamens are transformed carpels. 

 We might thus have new means of knowing the organic 

 symmetry of beings. 



Section XVIII. 



General Conclusions and Considerations upon the Struc- 

 ture of Flowers. 



It results from all the preceding Sections, that a flower, 

 considered anatomically, is composed of several verticils 



