RED-CLOVER SEED PRODUCTION. at 
and flattening them with a little pressure on the cover glass, the 
pollen tubes could be traced through the stylar canals, as pollen tubes 
have a denser and more granular content than the cells of the style. 
An examination of 30 flowers which had been self-pollinated for 55 
hours showed good germination on the stigmas but no fertilization. 
The number of pollen grains germinating on the stigmas ranged 
from 3 to 25 in each of the 30 flowers. The tubes had made a slow 
growth and none exceeded 4 millimeters in length. An examination 
of 20 flowers which had been self-pollinated for 90 hours showed that 
one pollen tube had attained a length of 7.5 millimeters, while the 
others were 5 millimeters or less in length. At this rate of growth 
the longest tube would have required about 48 hours more to reach 
the ovules, or about six days to traverse the entire distance from 
stigma to ovule. Flowers examined four days after springing the 
carinas showed the eggs in a disintegrated condition. It is therefore 
probable that in case of self-pollination the pollen tubes do not reach 
the ovules in time to effect fertilization. 
An examination of the 30 flowers which had been cross-pollinated 
for 55 hours showed that fertilization had taken place in all of them. 
CROSS-POLLINATION AND SELF-POLLINATION OF RED CLOVER. 
The results published by previous investigators on the cross- 
pollination and the self-pollination of red clover do not agree. These 
investigators appear to be about equally divided as to whether red- 
clover flowers are self-fertile or not. The experiments of Frandsen, 
according to Lindhard (23), Fruwirth (12, p. 163-166), and others 
show that red-clover heads which were covered during their blooming 
period and not pollinated failed to set seed Frandsen and Fruwirth 
also show that pollen must come from an entirely separate plant 
in order to fertilize the ovules of red-clover flowers. On the other 
hand, Garton, according to McAlpine (24) states that self-pollination 
is as common with red clover as it is with the bean. 
The relative efficiency of the bumblebee and honeybee as cross- 
pollinators of red clover has also been discussed by scientific investi- 
‘gators, as well as by agricultural papers and bee keepers. Bee men 
generally agree that the Italian race of honeybees can extract nectar 
from red-clover flowers. Little has been said, however, about the 
ability of the honeybee to collect pollen from red clover. 
In view of the above diverse opinions in regard to the self-pollination 
and the cross-pollination of red clover, a number of experiments were 
outlined in order to determine (1) whether red-clover flowers were 
self-fertile; (2) if self-fertile, whether any effective method of self- 
pollination could be found which would be applicable for use on a field 
scale; and (3) the relative efficiency of the bumblebee and honeybee 
as cross-pollinators of red clover. 
