368 The Journal 
of one variety. It should, however, be 
borne in mind that it is nectar that the 
bees are after, and they are not con- 
cerned with cross-pollination, so that if 
there is one variety rich in nectar, 
there is no reason why the bees should 
do anything more than simply work 
backwards and forwards between the 
hive and this block. I have noticed 
that the plum, Denniston’s Superb, is 
extremely rich in nectar, I have seen 
this variety carrying heavy crops of 
fruit, year after year, and I am inclined 
to think that its prolific quality is due 
to its richness in nectar attracting the 
bees. 
It is sometimes stated that wind is 
an agent in bringing about the pollina- 
tion of fruit trees. With some plants 
it undoubtedly is—in fact many are 
elaborately adapted for wind pollina- 
tion, the pollen-grains' of some cone- 
bearing trees having wings which enable 
them to be freely carried by the wind. 
To endeavour to discover what part 
wind plays in pollinating fruit trees, we 
enclosed two young standard plum 
trees in muslin of a mesh sufficiently 
small to exclude bees and large flies but 
large enough to admit wind freely. 
One of these trees, a Victoria, bore one 
fruit; the other, a tree of Reine Claude 
Violette, did not develop a single fruit, 
whilst neighbouring Victoria trees carried 
quite fair crops. Both these varieties 
are self-fertile, and this clearly shows 
whether a tree be self-sterile or not. 
Insects are absolutely necessary for 
efficient pollination. 
Another experiment has shown that 
the stigma, under the best conditions, 
begins to deteriorate to a marked 
extent, in regard to its receptiveness of 
pollen, the eighth day after the flower 
has opened and with climatic conditions 
so adverse as is usual with us in the 
spring, during the period the trees are 
in flower, its receptiveness is probably 
of much shorter duration. 
With such existing conditions as 
these, the value of having hive bees in 
the vicinity, so that they can work 
freely on the flowers during the short 
bright spells which often occur during 
weather which prevents them leaving 
the hive, cannot be. easily over-esti- 
of Heredity 
mated. The value of the wild bees and 
other pollinating insects, should not be 
over-looked, as they work more freely 
than the hive bees during adverse 
weather. 
THE EFFECT OF RAIN 
The effect of rain upon fertilisation is 
not, to my mind, so deleterious as is 
generally thought, for experiment has 
shown that the application of water on 
the stigmatic surface, two hours after 
pollination, has no effect whatever in 
preventing fertilisation taking place, 
and it is probable that it would not at a 
much shorter period if weather condi- 
tions were favourable. The applications 
of water were much more severe than 
would occur in a practical way from a 
shower of rain, and, considering the 
small size of the surface of the stigma, 
I think that the water that would come 
in contact with and remain upon it is 
hardly worth considering. <A period of 
rain, however, would doubtless destroy 
much pollen, and prevent pollination 
taking place. 
The phenomenon of self-sterility pre- 
sents but half the problem of the pollina- 
tion of fruit. There is yet the question 
of satisfactory pollenizers, and this is 
of most importance. Taking the ex- 
treme for an example: several cases 
have been found where distinct varieties 
are of no use whatever as pollenizers 
for some other varieties. After exten- 
sive experiments with Coe’s Golden 
Drop, Jefferson and Coe’s Violet, there 
seems but little doubt that, however 
these three varieties of plums are inter- 
crossed, no fruit will set. Coe’s Violet 
is supposed to have originated as a bud 
sport from Coe’s Golden Drop; if this is 
correct an explanation is presented, as 
it would be really a part of the same 
individual. In the case of Jefferson, 
however, no explanation can be offered 
at present. All these three varieties 
have been crossed with several other 
varieties, and have set and developed 
excellent crops. 
Excepting the crossing of distinct 
species, I am inclined to think that these 
extreme cases of physiological differ- 
ences may be rare in plums of the 
domestica group. With apples, how- 
