194 
Fig. 1. 
e 
8. 
Mr. Brown on the Organs and Mode of 
EXPLANATION OF THE PLATES. 
Tas. 34. AsCLEPIAS PURPURASCENS. 
A branch in flower : —natural size. 
An expanded flower, of which two of the foliola coronz 
and one of the anthere are removed :—moderately 
magnified. 
A front or inner view of an anthera, to show the extent 
of bursting, particularly with relation to the pollen 
mass, of which the greater part is included in the non- 
dehiscent portion :—magnified as fig. 2. 
A pollen mass, more highly magnified, separated from 
its gland and arm, and divided transversely, to show 
its cellular structure (first discovered in Asclepias cu- 
rassavica in 1805 by Mr. Bauer), with grains of pollen, 
their granules, and some drops of an oily fluid. 
A pollen mass entire, with a small portion of the arm 
adhering to its apex :—magnified as fig. 4. 
A transverse section of a pollen mass, still more highly 
magnified, in one of the cells of which is seen the 
single grain (or inner membrane), also separately ex- 
hibited to show that it is simple and slightly angular. - 
. The pistillum with pollen masses, that have burst and 
protruded their tubes, applied to the base of the 
stigma, the glands and their arms being removed. 
The cords formed by the pollen tubes have passed 
along the corresponding sides of the conical base of 
the stigma, and have reached the tops of the styles. 
A longitudinal section (more highly magnified) of the 
conical base of the Stigma with the two styles, to 
show more distinctly the course of the pollen tubes. 
Fig. 9. 
