1918] BRIEFER ARTICLES 177 
For class use, where very thin sections are not ordinarily required, 
we have found that the temperature of the knife in such a holder is 
sufficiently low if tap water is allowed to flow through the tube. A 
very short time is required for the temperature of the water to be com- 
municated to the knife. A cooling cell such as LAND’s or GARDNER’S 
also regulated with tap water may be employed in addition, but its use 
ase <i | 
UT RES __ 
pe 
in most cases is superfluous. Where sections from soft or medium 
paraffin under 5» are required, the modified safety-razor blade holder 
and the cooling cell are attached to GARDNER’S apparatus with the 
buckets filled with ice water. Under such conditions sections 2 » thick 
have been cut very successfully from a paraffin melting at 53°.—T. H. 
GoopsPEED, University of California. 
POLLINATION OF ASCLEPIAS CRYPTOCERAS 
Being interested in the mode of pollination of Asclepias, I should 
like to know how Payson explains the mode of pollination given in Bor. 
Gaz. 61:73. 1916. By a bumblebee’s foot I understand the end of the 
last tarsal joint with two claws and a pulvillus. Does the corpusculum 
become attached to the foot or to one of these appendages? If the foot 
is wedged between the anther wings, how does the bee get away without 
tearing the anther wings, and how does it, or any part of it, enter the 
cleft of the corpusculum? In pollination, if the bee pulls out its foot 
with attached corpusculum, what keeps the pollinium from coming out 
with it? My view of the pollination of Asclepias, published in Bot. Gaz. 
11: 262-269. 1886, and 20: 110. 1895, is that a single claw, hair, pulvillus, 
tibial spur, or stump of a retinaculum is caught in the slit between the 
anther wings and is guided by them into the cleft of the corpusculum. 
The corpusculum keeps this appendage from again entering the slit. 
Only one pollinium is caught between the wings and guided into the 
stigmatic chamber, where it is held so firmly that a pull breaks it loose 
from the retinaculum. Probably Asclepias cryploceras is a bumblebee 
flower, but I would not accept the view that it is not occasionally 
pollinated by other long-tongued bees, or butterflies, unless it is shown 
that these insects do not have proboscides long enough to reach the 
nectar.—Cnar es Rospertson, Carlinville, Il. 
