The Scottish Naturalist. 215 



in the scapes. Possibly they may be the work of the same species 

 as makes the second kind of galls just mentioned on P. lanccolata, 

 as the galls are so similar on the two plants. On P. maritima 

 they are conspicuous, as they enlarge the part attacked to as 

 much as four times the normal breadth, and usually assume a 

 pale yellowish green, less often a red or purple shade. There is 

 often marked distortion in the structure of the galled parts. The 

 deviations from the healthy state caused by the gall will be besr 

 understood after a brief sketch of the transverse section of a 

 healthy leaf. A normal section shows a very regular arrangement 

 of its tissues, viz., the epiderm all round the mesophyll, which is 

 made up of oval thin- walled cells, lying so that their long axis is 

 at right angles to the surfaces. Usually about 9 layers of cells 

 can be made out between the epiderms, those in the middle 

 usually being rounder and smaller than the others. There is no 

 distinction recognisable into palissade cells and loose layers, and 

 the interspaces, though numerous, are all small and nearly equal. 

 The fibro-vascular bundles lie in a row in the middle layers of the 

 leaf, and are hardly at all altered in the galls. One can usually 

 distinguish a mid-rib, and on each side of this two lateral bundles : 

 and between the five large are several smaller bundles. 



The galls differ from the above in structure almost solely in the 

 mesophyll, of which only a part may be altered, or the gall may 

 extend the full breadth of the leaf. At times the galls reach 

 15mm. in breadth, but they are in general considerably smaller. 

 On making a transverse section of a gall, one finds the cells of the 

 mesophyll much elongated and irregular in form, assuming the 

 type known as branched parenchyma, so that large intercellular 

 spaces are formed. In these spaces lie numerous "worms," which 

 I was able, after examining all stages and both sexes, to refer to 

 the genus Tylenchus of Bastian, but they differ from any species 

 of which I can find descriptions in Bastian's Monograph on the 

 Anguillidae {Trans. Linn. Soc, vol. xxv). The epiderms of the 

 galls have fewer stomata in proportion, and their cells are hardly 

 so regular as in the healthy leaf. The galls are abundant on the 

 ■coast of Kincardine all summer and autumn. 



VERONICA OFFICINALIS L. :— 



Flowerbuds galled by Cecidomyia {? Veronica JBremi), quite 



similar to those already described by me (Sc. Nat., iv., 170) on 



V. Serpyllifolia. The buds swell to twice or thrice their normal 



size, and remain unopened or open but slightly. They may be 



rather pale green, or the petals may show slightly and of the 



