352 ARACHNOIDEA. 



CAGE answer, at least to a certain extent, viz., so far as regards those tliat 



XVI. J 7 O 



live in buds. These have been found already established in No- 

 vember in the young buds of the currant, which are then elabo- 

 rating for development in spring, but whether they are torpid 

 through the winter or not we do not know, most probably they are. 

 But what becomes of those that live in galls on leaves, and not in 

 buds, and what becomes of some of them, at least between spring, 

 when they are in myriads, and autumn ? In summer we see none 

 of the bud species ; the buds are gone, destroyed by these 

 creatures — but what becomes of them then? Again, how do they 

 spread ? we may assume that they do so very slowly, for although 

 when a tree has once become attacked by these Phytopti it 

 continues to be so year after year, other trees of the same kind 

 standing around it are often perfectly free and untouched. The 

 same circumstance has been observed of other galls ; some species 

 of oak-galls having been known for many years to be confined 

 to individual trees, and not to have spread to others at no great 

 distance. This is not without its advantages for observation; 

 anyone who has a tree that is once infested with mite-galls near 

 his house should be able to watch for their very earliest appear- 

 ance, and study the whole course of their development under the 

 most favourable conditions; and one of the most curious and 

 important of these points must be how these slow-moving, almost 

 stationary animals manage to spread themselves all over the buds 

 of a tree, or over a whole hedge, or to any solitary individual tree. 

 We do not see them moving about during the day, but they may 

 wander at night, the sun's rays might be too strong for such im- 

 palpable globules, and dry them up. Anyone who has tried to 

 examine them under the microscope knows how likely this would 

 be. But here again there is a difficulty, they seem incapable of 

 continuing to move in any definite direction for any time. They 

 waggle about in an aimless way, turned from their path by any 

 obstacle, such as meeting one of themselves ; and it is difllcult to 

 conceive them spreading any distance from the spot where they 



