Sargent . — Notes on the Life- History of P ter o sty Us. 271 
insects hovering over the labella just as bees do over nectariferous blossoms. 
On one occasion I saw a little dipteran sucking juice from the top of a large 
appendage of a P. Sargenti labellum. I have noticed also that the diptera 
which visit P. Sargenti flowers are often in no hurry to leave their prison, 
when hurled into it. Quite unconcernedly they employ their time in suck- 
ing juice chiefly from the lower part of the column. One sometimes 
continues thus employed till the labellum falls and allows it to escape without 
crawling through the column wings. After such a long stay in the flower 
the insect always seems rather stupid and disinclined to fly, until it has 
spent a few minutes in the open air. Its behaviour suggests intoxication, 
though it walks quite steadily. A fortunate accident gave me the hint that 
‘ blow flies ’ are fond of the juice of these orchids. Acting on the hint, 
I caught a few vigorous flies and imprisoned them under a bell-glass 
along with a watch-glass containing a crushed P. recurva blossom. Very 
soon the flies were greedily feasting on this. At first they were easily 
disturbed ; but it gradually became difficult, and finally almost impossible, 
to drive them from their booty. Then they seemed unable to fly, though 
they could walk perfectly. I replaced the Pterostylis flower with a dish of 
pure water, and the flies rapidly regained their former liveliness. At another 
time I saw a blow fly greedily sucking the top of the ovary of a P. recurva 
flower, from which I had cut the perigone and column. This fly clung 
tenaciously to his prize when I tried to pull him off. As soon as I let go 
he sprang back, as though his legs were rubber bands fastening his body 
to the ovary, and recommenced sucking immediately. Even tickling his 
proboscis with a stiff bristle made no impression upon him. Similar 
experiments with P. Sargenti blossoms gave concordant results. 
I think it is safe to conclude that the flowers contain an intoxicating 
principle highly attractive to the insects which visit them. I may here 
remark that tiny insects (diptera) are not infrequently found dead in the 
flowers, usually adhering to the stigma. The stigma is so slightly sticky, 
indeed it is scarcely more than moist, that I have always very much doubted 
its ability to hold a living insect, even though so small a one. I now feel sure 
that these little flies found dead in the flowers are victims to their unbridled 
appetites. Only once have I seen a visit to a flower carried completely 
through. I will briefly describe it. On July 17, 1907, a vase containing 
several racemes of P. vittata was standing close to my window. At about 
3 p.m. I noticed a small ‘ gnat ’ hovering over the flowers apparently choos- 
ing a labellum to settle upon. Soon it did alight on one, but quickly flew 
off again. It shortly returned, and again settled on the same labellum. It 
settled near the apex and gradually moved up to the base of the lamina. 
I believe it then thrust its proboscis into the fleshy tissue of the appen- 
dage. Then the labellum immediately sprang back, and made the gnat 
a prisoner. After fluttering about for a few seconds in the lower chamber, 
