Fecundation in Orchidee and Asclepiadea. 131 
apparently additional part, not met with in other families ; the 
second, the cohesion of the grains of pollen, and their applica- 
tion in masses to the female organ. 
With regard to the first peculiarity it may be observed, that 
there is no real addition made to the number of organs in either 
family, and that in both families the apparent addition consists 
in a modification or production of the stigma; the modified 
part of which loses the proper function of that organ. 
This production of the stigma,—which is generally present, 
and wanting only in certain Orchidezx, where its place is some- 
times supplied by an analogous modification of the male organ, 
—though differing very remarkably in appearance in the two 
families, agrees in being originally distinct from the pollen 
masses, and in the advanced stage becoming firmly attached to 
them ; in adhering but slightly to the point of its formation 
after the attachment to the pollen takes place; and in being so 
constructed as to be readily removed by insects from its original 
position along with the pollen masses. 
As to the second point of agreement; namely, the cohesion 
of the grains of pollen into masses of considerable size, and the 
application of these masses to the stigma,— it is obviously con- 
nected with that which might perhaps be termed a third pecu- 
liarity; the apparent necessity for an unusual number of pollen 
tubes which are to act in concert ; in the one family to penetrate 
to and regularly arrange themselves in the cavity of the ova- 
rium*; in the other, to open a communication with the stigma, 
and then to pass along a non-secreting surface, until they arrive 
ata distant point, where they are to be introduced into the 
cavity or body of the style. 
With respect to the agency of Insects in fecundation in those 
two orders, there can be no doubt that it is very frequently em- 
ployed in Orchidee ; at the same time there are evidently cases 
* See Additional Observations. 
in 
