106 BRITISH OAK GALLS. 
bushes and young trees in woods are sometimes badly 
attacked. Fully developed trees do not often bear 
alls. 
i Towards the end of September, or early in October, 
the parent Cynips emerges from a gall of the year, 
and at once seeks leaf buds in which to oviposit. She 
appears to prefer buds on slender and delicate twigs, 
but occasionally pierces those on the sides of larger 
branches. As soon as the egg is deposited, growth 
and development begin. A blastem forms around the 
ege and the larva hatches. A small and inconspicuous 
“swelling is then formed on the twig. Very slight 
increase takes place until the following April or May. 
The embryo gall then becomes more readily noticeable, 
and by the end of June it will have attained the size 
of an ordinary pea, bright green in colour if exposed 
to the light, but golden yellow if im deep shade. 
Many specimens are also tspotted, or streaked with 
crimson. Until the gall attaims several millimetres in 
diameter, the tissues are enclosed within an epidermis 
which contains a reddish sap. Few or many one-cell 
hairs are scattered over its surface. 
During July larva and gall rapidly enlarge; the 
epidermis, not keeping pace with the increase, splits 
into numerous small scales which quickly fall off 
leaving the surface a beautiful apple-green colour. 
Early in August considerable internal changes take 
place, the principal being that the primary nutritive 
tissue disappears, and oil globules and several pro- 
teids form the food of the occupant of the cell, the 
walls of which harden considerably. Little change 
is then noticeable except in coloration, until the 
latter part of September. The structure has then 
become firm and hard. It has attained maturity, 
and assumed a_ brownish-yellow' or reddish-brown 
hue. It is firmly attached to the seat of growth, 
and will maintain its position for two, three, or 
more, years, neither wind, rain, hail, nor frost, dis- 
lodging it. 
