246 BOTANICAL GAZETTE. [ October, 
linia, on another fifty-four. I have also found a pair of pol- 
linia on a hair of the abdominal brush of Megachile. Next 
in abundance to bumble-bees, is Bembex nubillipennis, which 
rests so lightly on the flowers and has such short hairs that I 
ave failed to find pollinia upon it, except in one case, men- 
tioned below. One beetle, Trichius piger, caught on a 
Pycnanthemum, has eight corpuscula and eight pollinia on 
ventral surface. Butterflies rarely force their thin tongues 
into the nectaries, but do not extract the pollinia. Flies were 
not seen sucking. 
In Acerates viridiflora, the tips of the hoods rise to the 
level of the style-table, while in this species they hardly reach 
to the angles of the wings, and it is interesting to observe 
the effect. In sucking, the insect’s head is brought down so 
close to the tips of the hoods that the hairs on its face and 
tongue are often caught by the wings; indeed, it seems more 
natural for visitors of this Acerates to have pollinia on their 
tongues than for those of Aclepias. Pollinia were found’ on 
the hairs of the labrum and tongue of Bombus separatus, 
and on the labrum of Bembex nubillipennis. Fig. 5, @ 
sketch of the face of Cerceris bicornuta, indicates the posi- 
tions of attachment of three corpuscula with five pollinia- 
The specimen also has pollinia on the tongue, and five cor- 
puscula with eight pollinia on ventral surface. 
: ave seen no combinations of pollinia of this plant, and 
it does not seem to need them, as it can attach an abundance 
of corpuscula directly to the hairs. 
_ The pollinia turn with their blades parallel in about @ 
minute after extraction. When the bee moves over the 
flowers a retinaculum with its pollinium is caught as the hair 
was before. When the pollinium has entered the stigmatic 
chamber and will go no further, the retinaculum is broken, 
leaving the pollinium in. the cavity, and escapes from the slit 
without withdrawing the corpusculum at the top. That the 
corpusculum does not enter the chamber, but that each pol- 
linium is inserted singly, I am satisfied is true in this plant 
as well as in Asclepias. It is hardly possible to see pollina- 
tion effected, as in Asclepias Sullivantii, but I have found 
pollinia under conditions which indicate that they are int" 
duced in the same manner. A pollinium is sometimes found 
in the stigmatic chamber with pollen tubes emitted, with 16 
retinaculum projecting through the slit, and the corpusculum 
and the other pollinium hanging outside. Broken hairs 1D 
the cleft of the corpusculum show that it has lost its hold oF 
