No. 468.] THE WILLOW CONE GALL. 863 
ing twigs growing under similar conditions. The former aver- 
aged three more lateral buds to a twig than the latter. From 
another clump of willows 14 twigs bearing pubescent galls had 
an average of three buds fewer than 14 non-gall-bearing twigs 
(15 and 18) but the average length was equal. 
I conclude. that the gall does not represent a shortening of 
the axis and that the gall-bearing twig does not represent a 
lessened growth, but that, on the other hand, the gall-bearing 

The larger shows protruding pupal skins 
Fic. 2.— Two cone galls showing extremes in size. ' ! 
i d stem of the smaller is a bud favorably 
of the moth Acleris. At the base of the crooke 
placed for continuing growth in a direct line. 
twig holds its own with the non-gall-bearing and has in addition 
the abnormal growth of the gall. 
The very abnormal shape of the stem of the crooked gall sug- 
gests a question as to its purpose. Since the gall terminates 
the twig and prevents further apical growth, future growth must 
