H. C. Botanic Gardens^ Calcutta, 



25S 



placentae, is not borne out by development, which shews the 

 central cone to be formed before the carpel leaves. Yet so 

 far as my observations go, the placentae when manifestly, as 

 they so very generally are, referrible to the carpel leaves, 

 are of considerably later development than the leaves to 

 which they belong. 



The explanation that seems to me to accord best with 

 observations of the development, and to explain also the 

 general structure in the best way is, that the placenta 

 in this plant is the conical termination of the axis, produced 

 upwards into a styliform stigma, and bearing round its 

 base, at or about the plane of insertion or attachment of the 

 carpel leaves, a verticillate series of ovula. And if it be 

 found to be correct, it appears to me strongly in favour of an 

 opinion lately advanced by me that, even when the style is 

 present, the stigma may be quite independent of it. 



This hypothesis does not explain the appearances pre- 

 sented by the expanded flower more fully than the preced- 

 ing, but then it appears to me to agree with the development, 

 and especially the primary appearance of the central cone, 

 and also with the evidently more intimate relations of the 

 very young ovula with the base of the cone rather than 

 with the margins of the carpel leaves. Moreover, a cen- 

 tral axile placenta terminating in a stigma, appears to me 



stance of these consist of the possibility of the stigma being a continua- 

 tion of the placental margins of the carpellum, of its being the external 

 communication of the conducting tissue, which itself communicates with 

 the placentae, and is in several cases at least manifestly identical with 

 them. That the phrase " stigmata opposite to the placentae" arises 

 from a cohesion between stigmatic surfaces, analogous to that cohesion 

 which causes in fruits the loculicidal dehiscence. That Orobanche pre- 

 sents owing to this cohesion right and left stigmata, as is proved by 

 development and the situation of the vascular fascicles of the style 

 &c. &c. and that the stigma being an extension of a mere cellular surface 

 need not present any definable form, and that it may exist indepen- 

 dently of the style. 



