NOTES ON THE DRY SUMMEB OF 1896. 177 



summer, that 1782 was still worse, and in fact, a year of famine 

 in the north-east of Scotland." As the meteorological conditions 

 of those two summers were thus recorded in the heart of ash 

 stumps, so our alder, larch, and apple-trees last summer wrote 

 their own histories. Years hence it will be found that the layer 

 of wood formed during the summer of 1896 was narrower than 

 those of the preceding and probably succeeding years. 



In a few places the black poplar suffered from the ravages 

 of a pest closely resembling that which devoted its attention 

 to the alder. In this instance the foe was the Poplar-Beetle 

 (^Chrysomela populi). Larvae and beetles infested the leaves at 

 one and the same time, the latter being very small and of a 

 beautiful metallic blue colour. The larvae can be distinguished 

 from those of the alder-beetle by their peculiarity of feeding 

 side by side like a line of well-trained soldiers. This important 

 distinction I have not noticed in books bearing on the subject. 



We now pass on to the oak. Prolific in blossom and fruit, 

 and bearing leaves of more than ordinary size ; this tree has 

 also had its enemies. Of the forty or more Galls found on the 

 oak, many of the more interesting were among us last summer. 

 Not to mention them all, it may be stated that we had the 

 Currant-Grail, caused on the lower surface of the leaves and on 

 the catkins by Spathegaster baccarum ; the Artichoke-Q-all, a scaly, 

 bud-like growth, produced at the ends of the branches by Cynips 

 gemmce ; the Common Oak-Gall, the work of Cynips foUi ; the 

 Sponge-Gall, resulting from punctures by Teras terminalis ; and, 

 in the autumn, those interesting little Oak-Spangles, formed on 

 the under surface of the leaves by Neuroterus lenticular is. Thanks 

 to the investigations of Dr. Adler, Mr. Walsh, and others, the 

 relationship between the spring and autumn galls is no longer 

 a mystery. It is now abundantly clear that the two successive 

 generations of a species differ in every respect from each other ; 

 that, in short, the progeny of the insects which cause the spring 

 galls, not only produce a different kind of gall in the autumn, 

 but, the insects themselves differ so greatly from their parents 

 as to be considered distinct species. This will be better 

 understood by citing an example. In the spring an insect 

 known as Spathegaster baccarum gives rise, on the leaves and 

 flowers of the oak, to those berry-like growths known as Currant- 



