38 Mr. R. Brown on the relative position of 



structure, though in some families hardly of generic import- 

 ance, seems to me to assist in explaining the apparently ano- 

 malous structures of Hydnora, Rafflesia, and Brugmansia. 



On the subject of the origin and type of Stigma, my first 

 observation is, that the style where present can only be re- 

 garded as a mere attenuation, in many cases very gradual, of 

 the whole body of the ovarium. Hence the idea naturally 

 suggests itself, that the inner margins of the carpel, which in 

 the lower part are generally ovuliferous, in the upper part 

 perform the different, though in some degree analogous, func- 

 tion of stigma. As the function, however, of this organ implies 

 its being external, and as in different families, genera, and even 

 species, it has to adapt itself to various arrangements of parts 

 destined to act upon it, corresponding modifications of form 

 and position become necessary ; hence it is frequently con- 

 fined to the apex, and very often, especially in the com- 

 pound ovarium with united styles, appears to be absolutely 

 terminal. 



In such cases, as it must always include and be closely ap- 

 proximated to the vascular cord of the axis, it has by some 

 botanists been considered as actually derived from it, which 

 it is, however, only in the same manner as the marginal pla- 

 centae are derived from the axis of the carpel. But according 

 to the notion now advanced, each simple pistillum or carpel 

 has necessarily two stigmata, which are to be regarded, not as 

 terminal, but lateral. 



That the stigma is always lateral may be inferred from its 

 being obviously so in many cases; and in one genus at least, 

 Tasmannia, it extends nearly the whole length of the ovarium, 

 so as to be commensurate with and placed exactly opposite 

 to the internal polyspermous placenta. 



That the stigma is always double appears probable from 

 those cases in which it is either completely developed, as in 

 the greater part of Graminece where the ovarium is simple ; 

 in the compound ovarium in Urena ; and from those in which 

 the development, though less complete, is still sufficiently ob- 

 vious, as in many Euphorbiacece and in several Iridece. This 

 degree of development, however, is comparatively rare, con- 

 fluence between the two stigmata of each carpel being the 

 more usual structure ; and in the compound pistillum a greater 

 degree of confluence often takes place in the stigmata than 

 in the placentae ; — a fact, which in all such cases is obviously 

 connected with adaptation of surface to the more complete 

 performance of function. 



Another difference frequently occurs between the mode of 

 confluence of placentae and stigmata, namely, that in the com- 



