INTRODUCTION 
ii 
2. Galls at Base of Shoots 
The base of a shoot alone is involved; the upper part is 
able to continue its growth beyond the gall. This group 
includes the pineapple galls of the Spruce caused by 
aphides (Plate X.), and the spongy growths on various 
Bedstraws caused by the dipteron Perrisia galii (figured 
in Chapter V.), also on cruciferous plants by Dasyneura 
sisymbrii. 
3. Rosette Galls 
Axis of the bud much stunted, covered with densely 
crowded leaf structures, between which the insects live. 
(a) Developed in the Foliage Region 
These galls resemble a miniature rosette, double Rose, or 
Cabbage. Well-known examples are the rosettes at the tops 
of Willow twigs caused by the dipteron Rhabdophaga rosaria , 
and those on Hawthorn twigs caused by an allied insect, 
Perrisia crataegi. 
(b) Developed in the Floral Region 
Bunches, rosettes, and balls, take the place of flowers. 
Very common instances are the whitish hairy gall at the 
top of the shoot in the Germander Speedwell, resulting from 
attack by the dipteron Perrisia veronicae (Plate VIII.), and 
the tuft of crowded erect leaves at the tip of a shoot in the 
Yew, caused by the presence of the larvae of the dipteron 
Oligotrophus taxi. An uncommon but very distinctive gall 
belonging to this section is the tassel-like growth caused 
by the homopteron Livia juncorum in the heads of various 
Rushes. 
FUNGUS GALLS 
1. On Part of the Foliage Leaves 
The curious galls known as “ Alpine Rose-apples,” 
frequent on the Continent on leaves of Rhododendrons 
