Black-currant Gall-mite . 
179 
point would be most welcome, there seems to be sufficient 
indirect evidence to warrant us in believing that it is always 
the plant, and not the ground, which harbours the mite. In 
the first place, numerous migrating mites have been allowed 
to fall upon soil, and have been kept under observation under 
the microscope until they died. They never showed signs of 
having reached a congenial environment — as they naturally 
would if they sought the ground to hide there. They did 
not conceal themselves or lay eggs, but wandered restlessly 
till they died. In the second place, all the variable results of 
severe pruning can readily be explained on the supposition 
that in some cases mites obtain shelter very low down on the 
plants, whereas, if the ground remains infested, some of the 
results are quite impossible to account for. 
Take such a case as that communicated recently by a 
member of the Society. Of two dozen infested bushes, he, 
three years ago, treated half by cutting out all the new wood 
at the end of June and dressing the plants with lime. The 
remaining dozen he cut down to within six inches of the 
ground. The first lot showed a great improvement the follow- 
ing year, but the disease recurred. The more severely pruned 
bushes had no recurrence of the mite, and this year bore a 
heavy crop. Now if the soil was a source of infestation, there 
is no reason why any of the bushes should have escaped ; 
while those cases in which the disease appears again in plants 
which have been entirely cut down can be still accounted for, 
so long as any of the plant remains, on the supposition that 
occasionally the mite contrives to conceal itself very low down 
on the stem. 
Moreover, there are several cases on record where old 
diseased bushes have been replaced by new plants without any 
treatment of the ground, and have proved free from disease. 
In those instances where they have exhibited it they were in 
all probability diseased when planted, for it is quite possible 
for young plants to appear quite clean, and yet to contain 
enough mites to develop the disease in a severe form. 
It is desirable to sum up briefly what is now known with 
regard to the life-history of this pest. 
Eggs have been found within the buds during every month 
of the year. The mites inhabit the centre of the buds, spread- 
ing towards the exterior as they increase in number. In 
the spring the slightly infested buds are not prevented from 
opening, and the mites are obliged to leave ; but having as yet 
no new buds to enter, they perish unless they can live in the 
ground, which does not appear to be the case. The badly 
infested buds do not open, but harbour the mites till they 
become dry and brown, when a definite migration takes place. 
