ANDRICUS RAMULI. 69 
It is undoubtedly one of the most distinctive and 
delicate galls of the oak. 
So far as my observations of this species have 
extended, it appears that it may be found more 
frequently on Q. sessiliflora than on Q. pedunculata. 
On the continent, however, Q. pubescens seems to be 
the favourite tree. 
This interesting and most attractive growth is one 
which commands more than a passing notice from all 
persons who see it for the first time. It has the 
appearance of a tuft of white cotton-wool, and among 
the green leaves and yellowish catkins it looks 
exceedingly pretty and dainty. 
These galls attain maturity of form very rapidly, 
and the period during. which they retain their pristine 
beauty is also very brief; in sheltered positions it is 
from five to seven days. Considerable care must be 
exercised while gathering them. They are very 
delicate, and any undue pressure will compress the 
hairs and render it impossible to restore them to their 
original form. Heavy rain will also disfigure them. 
The hairs at first are more or less separate from each 
other; about 15-20 mm. long, somewhat glutinous 
and wool-like, and when in a mass are not resilient. 
The entire structure, or compound gall, consists of 
clusters of conglomerated larval chambers each of 
which constitutes a true gall. The clusters vary in 
number from two to ten, and contain about fifteen 
larval chambers in each. It is from these clusters the 
hairs grow, and being in close proximity to each other 
unite to form an oval or globular-shaped mass of white 
hairs, about the size of a walnut or a cherry respec- 
tively. 
In drying the mass diminishes to about half its 
original size. This is due to the contraction of the 
hairs, which become convoluted and interwoven. The 
colour changes to a yellowish-brown soon after 
maturity, and the imagines then make their exit. The 
galls occasionally develop from a leat-bud. 
