282 
THE PLANT WORLD. 
feathery stigmas, the hop “ brush." In this condition hops are 
said to be “ in burr.” As the stigmas drop off, whether fertiliza¬ 
tion takes place or not, there is a rapid growth of the strobile 
bracts, which produce the hop of commerce. The vines are now 
said to be “ in hop.” These strobile bracts contain lupulin 
glands with a secretion valuable for hop extracts used in yeast 
brews. 
Whether pollination is necessary or not seems to depend upon 
the variety used and climatic conditions. German investigators 
hold that pollination not only is unnecessary but harmful to the 
satisfactory market value development of the hop fruit. Hops 
from districts where male plants are not allowed are not seedless, 
however, showing that efforts for a valuable seedless variety are 
not as yet successful. In England, where another variety of hop is 
used and climatic conditions are damper, Kentish growers agree 
in the opinion that hop crops satisfactory in full and early ma¬ 
turity and in freedom from mould (Sphaerotheca humuli ) are 
only obtained when pollination is possible. Mr. Howard’s ex¬ 
periments during the summer of 1904 had led to the same con¬ 
clusion. He found that non-pollinated hops remained undersized, 
seedless, green, with unripe lupulin glands and little mould-re¬ 
sisting power, while fertilized flowers developed more rapidly, 
showed well formed seeds, bracts and lupulin glands, a bright 
yellow color and comparative freedom from moulds. This ad¬ 
vantage in mould-resisting power possessed by fertilized flowers 
is accounted for by the fact that the feathery stigmas, which 
easily attract mould spores, and afford good germination condi¬ 
tions, wither much more rapidly in fertilized than in non-fertilized 
specimens. The seed hop, developed by fertilization, therefore, is 
the only variety known as yet for cultivation in Kent. American 
growers find that unfertilized hops are light in weight with 
neither color, strength nor value. Further investigations along 
the same lines and also as to the brewing value of seed and seed¬ 
less hops, by determining the total amount of resins in each, are 
to be pursued, as far as possible during the present year. 
M. C. Chedsey. 
