254< On some remarkable Plants in the 



more reconcilable with a perfectly isolated stigma, than the 

 occurrence of such a stigma, in connection with carpel leaves, 

 from which it would then be supposed to originate, and 

 with which consequently it should at some period present 

 some degree of connection.* 



A necessary consequence of such an isolation of the stig- 

 matic tissues from the style, is that the course of the pollen 

 tubes will be downwards over the surface of the central 

 column. Appearances are I think in favour of this,f which is in 

 accordance with the course of pollen-tubes in many, and per- 

 haps in all cases, in which the stigmatic tissues are not con- 

 fluent at any part of their extent. The term penetration, 

 therefore, does not apply by any means invariably to any re- 

 lation effected between the pollen-tube and any part of the 

 female organ, except the ovulum, of which it affects only 

 the nucleus and embryo-sac. 



In either view it may be suggested from the small degree of 

 union between the carpel leaves and placentae, and particu- 

 larly from their apparently absolute distinctness at an early 

 period, and which is, perhaps, only reconcilable with my 

 hypothesis, that such an arrest of development may occur, as 



* I have not been able to satisfy myself of the exact limits of the 

 carpel leaves. The first parts developed have appeared to me those 

 opposite the stamina, in which case the rays may be considered as 

 indicating the lines of union. The alternation in this case is regular. 

 But immediately afterwards the parts opposite the stamina present 

 concave edges limited by the now projecting rays, and the whole 

 appearance suggests that the rays form the axes of so many carpel leaves. 

 And although in this case the two innermost series of development, 

 assuming the teeth between the stamina to represent an inner series of 

 stamina, will be opposed, yet I prefer adopting it to the other view, 

 which supposes the carpel puncta to present concave terminations, 

 in other words, that their sides reach a greater elevation than their axes. 



t It is also singular that the inner surface of the tube or style appears 

 in some degree stigmatic, and presents after application of the pollen 

 the usual appearances indicating the first steps of fecundation. 



