538 THE FERTILISATION OF FLOWERS. [PART ITI. 
wall, it is certain that the bees pierced the delicate inner membrane 
and sucked the included fluid. They doubtless pierced the tissue 
quickly and easily with the points of their maxille. 
My direct observations have shown that the three or four 
seconds spent by the bee on each flower is enough to permit 
the cement to harden and attach the pollinia firmly to the bee’s 
head; and by thrusting a pencil into the spur of O. mascula we can 
see that two to three seconds is enough to fasten the pollinia 
firmly. The bee always thrusts its proboscis once only into each 
flower, and accordingly each flower receives pollen from another. 
In O. mascula, the bending forwards of the pollinium occupies 
about forty seconds; it is rarely completed in twenty-five seconds. 
A bee which visits three or four flowers on a spike, spends three 
to four seconds upon each, and about two seconds in passing from 
from one flower to another ; so that at most it spends about twenty 
to twenty-two seconds on each spike. It has therefore passed to 
another spike before any of the pollinia belonging to the first have 
finished bending downwards. It seems therefore that not only 
is cross-fertilisation of separate flowers ensured, but even of 
separate plants. | 
I repeated these observations many times subsequently. I 
was wrong at first in supposing that the bee only pierced the 
tissue of the spur once, and I neglected to look for the punctures 
that the bee made. On June 13th, 1870, a hive-bee flew before 
my eyes into a flower of O. latifolia: it pierced the inner wall of 
the spur several times with the points of its maxille, and then flew 
away, bearing the two pollinia on its head, to a flower of Lychnis 
Jlos-cuculi. I gathered the flower immediately after the bee left 
it, and found the punctures visible from the outside as small, 
bright, elongated specks. Darwin observed Hmpis livida piercing 
the inner wall of the spur of O. maculata, and also found the 
punctures that it made. The question as to what insects seek 
in the flowers is now finally settled, and Delpino’s doubts (567, 
p. 16) concerning the accuracy of Darwin’s views are shown to be 
unfounded. 
382. ORCHIS MASCULA, L. :— 
Visitors : Hymenoptera—A pide : (1) Bombus hortorum, L.; (2) B. lapi- 
darius, L.; (3) B, confusus, Schenck.; (4) B. terrestris, L. ; (5) B. agrorum, 
F. ; (6) B. pratorum, L.; (7) B. (Psithyrus) campestris, Pz. ; (8) B. muscorum 
1.7 Nos, 1—7, observed by me, No, 8 by a friend of Darwin’s (Ann. and Mag. 
of Nat, Hist. Sept. 1869), 
