ON NORTH-WEST AMERICAN ALGÆ. 157 
Finally, the genus Catasetum is interesting in an unusual degree 
in several respects. The separation of the sexes is unknown in 
other Orchids, excepting probably in the allied genus Cyenoches 
and in one other member of the Vandee, namely, Acropera. In 
Catasetum we have three sexual forms, generally borne on separate 
plants, but sometimes mingled together; and these three forms 
are wonderfully different from each other—much more different 
than, for instance, a peacock is from a peahen. But the appear- 
ance of these three forms on the same plant now ceases to be an 
anomaly, and can no longer be viewed as an unparalleled instance 
of variability. 
Still more interesting is this genus in its mechanism for fertili- 
zation. We see a flower patiently waiting, with its antennsm 
stretched forth in a well-adapted position, ready to give notice 
whenever an insect puts its head into the cavity of the la- 
bellum. The female Monachanthus, not having pollinia to eject, 
is destitute of antenne. In the male and hermaphrodite forms, 
namely Catasetum and Myanthus, the pollinia lie doubled up like 
a spring, ready to be instantaneously shot forth when the antenne 
are touched. The disk end is always projected foremost, and is 
coated with viscid matter, which quickly sets hard and firmly 
affixes the hinged pedicel to the insect’s body. The insect flies 
from flower to flower, till at last it visits a female or hermaphrodite 
plant; it then inserts one of the balls of pollen into the stigmatic 
‘cavity. When the insect flies away, the elastic caudicle, made 
weak enough to yield to the viscidity of the stigmatic surface, 
breaks, and leaves behind the pollen-mass ; then the pollen-tubes 
slowly protrude, penetrate the stigmatic canal, and the act of 
fertilization is completed. Who would have been bold enough to 
surmise that the propagation of a species should have depended 
on so complex, so apparently artificial, and yet so admirable an 
arrangement ? 
Notice of a Collection of Algæ made on the North-West Coast of 
North America, chiefly at Vancouver's Island, by Davip IP 
Esq., M.D., R.N., in the years 1859-61. By W. H. Harvey, 
M.D., F.R.S. & L.S., Professor of Botany in the University of 
Dublin, &e. 
[Read February 20, 1862. ] 
SEVERAL parcels of Alga, collected by Dr. David Lyall on the 
coasts of Vancouver’s Island and in the neighbouring seas, and 
