302 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
abandoned every shred of hope that even in the smallest plantations hand- 
picking will avail. 
One other remark I should like to make, or rather to ask two no doubt 
very ignorant questions. First, is it quite certain that a different host- 
plant may not carry the pest over a different life stage ? Is it impossible 
for the (at least very closely allied) Phytoptus which attacks the buds of 
ixwts — is it impossible for it to pass over to the Black Currant, at the same 
time slightly modifying its bodily structure, if needs be, to suit its new 
environment ? I have been told that entomologists will not entertain the 
idea for a moment because of two additional bristles which the Currant 
Mite has more than the Nut Mite. But if that be the case, how do they 
account for any development ? May they not have here, actually under 
their eyes, a case of development to suit an altered food-plant ? And my 
second question is this : Is it impossible for the creature, in some elementary 
stage of its existence, to pass with the sap through the vessels and tubes 
conveying this liquid from the root to the bud — somewhat in the same 
way as the Trichinise we used to hear so much about were said to pass 
from the food eaten into the muscles of the arms and legs of the eater ? 
Mr. Newstead explained that the migration of Phytoptus from one 
district to another would be quite involuntary. Strong winds may take 
them bodily from place to place, and very probably birds and winged 
insects may also carry them considerable distances. The spread of the 
pest is, however, chiefly due to the transportation by infested nursery 
stock, and the propagation of infested cuttings. 
He also thought it possible that the infestation of Professor Henslow's 
bushes at Ealing may have been present prior to 1897, as he had observed 
instances where Phytoptus had existed in comparatively small numbers 
for several years without in any way affecting the crop of fruit. 
In reply to the Eev. W. Wilks Mr. Newstead said that, so far as had 
been at present ascertained, no knowledge of the alternation of generation 
existed in P. ribis or any other allied species of Phytopti ; and, further, 
he considered Phytoptus avellanae, infesting the buds of the Nut, to be 
quite distinct from P. ribis, and that the former species had never been 
known to pass from the Nut to the Currant. As to the second question, 
Mr. Newstead said he had, so far, failed to find a trace of any foreign 
organism within the tissues of the plant — i.e., in the vessels and tubes or 
cell structures. 
