The Scottish Naturalist. 1 7 



a rather prominent sharp knob at the tip, are naked, smooth, 

 and in colour are green or brown, with numerous short white 

 longitudinal streaks. The wall is rather thick, and the inner 

 gall is hard, but is closely united to the outer wall. Of the oak- 

 galls formerly described by me, I found at Forres, in the month 

 of September, galls of Andricus terminalts, BiorJiiza renuni, Dryo- 

 phanta fo/ii, D. divisa, Andricus curvator, Neuroterus lenticularis, 

 N. numismatis, and old galls of Spathegaster vesicatrix. Of 

 course the spring-forms had disappeared, but their occurrence 

 is indicated by the existence of the autumn-galls. The gall of 

 Cynips Kollari was shown me by Mr Smith, from Rafford near 

 Forres. 



Agrostis alba, L. — In the month of October I found, on 

 the coast near Aberdeen, galls 011 this plant. They are situated 

 on the leaf-blade close to where it joins the leaf-sheath ; or, in a 

 few cases, at distances not exceeding an inch from the sheath. 

 The galls are dull red-purple swellings, oval or linear, rounded at 

 the ends, and prominent below. They measure T V - \ by ^ T - ^V 

 inch. On making a transverse section of a gall it is found to 

 be due to enlargement of one side of the leaf, chiefly around 

 and between the midrib and the next longitudinal vein of the 

 leaf, seldom extending markedly beyond the midrib or reaching 

 the margin. All the features of the normal leaf can be recog- 

 nised both externally and internally in the gall, but considerably 

 altered. The affected part becomes twice or thrice as thick as 

 the healthy leaf. The cuticle becomes much thickened, and 

 the epidermal cells become less regular, thicker-walled, and seem 

 to form two or three layers of cells instead of one layer. The 

 chlorophyll becomes less abundant, and may be almost absent ; 

 and the cells that contain it in the healthy leaf are represented 

 in the gall by considerably larger cells, lying with their long 

 axis parallel to the surface of the gall. The thick-walled cells 

 that usually form a sheath around each fibro-vascular bundle, 

 and extend above and below it to the surfaces of the leaf, become 

 much less conspicuous in the gall. In the centre of the gall a 

 longitudinal cavity is formed, apparently by separation of the 

 cells ; it seems not to open externally. In this space live the 

 makers of the gall, — A?iguillulce, — usually in considerable num- 

 bers. In the galls that I examined were numerous eggs and 

 immature worms, but I found only one sexually mature female, 

 which agreed with Bastian's genus Tylenchus ; but in absence of 

 mature males the determination must remain uncertain for the 



VOL. VI. B 



