48 The Yew. [Sess. 



between one sexual brood and the next. Their forms differ 

 considerably in the successive broods ; certain of the genera- 

 tions designated emigrants are winged, others are wingless ; 

 but into the curious and complicated life-history of this group 

 it is unnecessary to enter, since aphis galls are only of 

 secondary importance. Enough has been advanced in this 

 paper, we hope, to convince the reader that the study of galls 

 and gall-flies opens up a large and interesting field of biologi- 

 cal inquiry in which many questions still await investigation. 



Any one desirous of pursuing the subject will find assist- 

 ance in Cameron's volumes on Phytophagous Hymenoptera, 

 published by the Eay Society ; Dr Adler's work on Oak-galls, 

 Connold's ' British Vegetable Galls,' the volume on Insects in 

 the Cambridge Natural Science Series, as well as Professor 

 Trail's papers on Dipterous Galls in the ' Scottish Naturalist,' 

 may also be consulted. 



[In illustration of the above paper, several beautiful hand- 

 painted sketches, illustrating the different kinds of galls, were 

 exhibited.] 



Y,—THE raw. 



By a lady member. 



{Read Jan. 22, 1908.) 



The yew is a well-known evergreen closely related to the 

 pines and firs. It is, however, classed higher in the vegetable 

 kingdom than it should be, for its fruit is not collected in 

 cones like the pines and firs, but grows singly and almost 

 unprotected. The leaves are thickly set on both sides of the 

 branch, and in the young leaf-bud the upper surfaces of the 

 leaves are directed towards the centre, although the shoot is 

 growing horizontally. To do this, the leaves growing on the 

 upper surface of a shoot must twist on their stalks. This may 

 be proved by taking a yew branch with quite young buds and 

 fixing it in a horizontal position with the lower surface up- 



