The Development of the Pollinium and Sperm- 
Cells in Asclepias Cornuti, Decaisne, 
BY 
C. STUART GAGER. 
With Plate VII. 
Introduction. 
T HE flower of Asclepias has always been of interest to 
botanists. It was studied as early as 1763 by Adanson, 
and later by Gleichen (1779) and by Sprengel (1793) l . The 
mode of occurrence of the pollen has been especially interest- 
ing. Loew (1895) mentions a paper by Kolreuter in which 
the ‘ hangenden Beutelchen/ later known as pollinia, are 
described as the * male genitals ’ of the plant, and these 
organs have also been similarly described by Baron Jacquin 
(1811). 
In 1831 Brown, who separated (1867) the Asclepiadeae as 
a Natural Order of plants from the Apocyneae of Jussieu, 
made the first serious study of their pollinia. His first paper 
on this subject appeared in 1809, but he failed to observe the 
grains of pollen, and thought that the pollinium consisted of 
one individual cavity filled with minute granular matter mixed 
with an oily fluid. In 1831 Bauer, an artist, offered to Brown 
for publication drawings of several Asclepiadeae, made in 
1 Referred to by Brown, 1833. 
[Annals of Botany, Vol. XVI. No. LXI. March, 1902.] 
