Orchids 301 
in each flower is so short—about four seconds— 
that the pollinia have not drooped sufficiently to 
fertilise one of them. By the time the bee has 
reached another flower-spike the necessary depres- 
sion has occurred, and the bee therefore cross- 
fertilises several flowers in succession. ‘This is, no 
doubt, the reason why so large a number of Orchid 
seeds are produced, most of the abundant seed- 
egos being fertilised. 
All these details, though given with particular 
reference to the Purple Orchis (0. mascula), apply 
in all essentials to the Green-winged Orchis (0. 
morio), the Marsh Orchis (0. latifolia), the Dwarf 
Orchis (O. ustulata), and other members of the 
genus. Fertilisation is effected in O. mascula by 
the visits of several kinds of humble - bees; 
O. morio and O. latifolia by humble-bees, hive- 
bees, and some of the smaller bees (Osmia, etc.). 
0. maculata is visited occasionally by humble- 
bees, but chiefly by the larger two-winged flies 
(Empis, Volucella, Hristalis, etc.). On 3rd July, 
1898, in woods near Dorking, I observed that a 
very large number of the flowers of O. maculata 
had been visited by small flies that had crept right 
into the spur, but had been unable to extricate 
themselves again. On many spikes examined, nearly 
every flower was thus to all appearance rendered 
useless. J regret that as I was a long distance 
from home I lacked the opportunity or appliances 
for dissecting out the fly, or for observing whether 
the ovaries developed. This appears to be a serious 
matter for the plant, and if the circumstance is at all 
common should lead to some new development whereby 
