41 
plants is attacked, and the plant soon withers up. The affected 
leaves are rather thick and fleshy, but are little altered in colour, 
though conspicuous from the exposure of the lower surface. The 
margins usually make one and a half or two turns, forming a tube 
in which one finds a few mites. The inner tissues of the leaf are 
very little altered, beyond being slightly hypertrophied in the 
cellular tissues, and the epiderm is far less modified than in 
L. autumnalis, The mites are of rather Jarge size for the genus 
Phytoptus. There are no hairs specially developed in the interior 
of the tube. [had observed similar deformities on H. Pilosella 
in Perthshire, and elsewhere in Scotland, before I had recognised 
their origin. They have been recorded from Germany and 
Switzerland (Thomas and Schlechtendal), and from Austria 
(F. Loew). 
_ (6) Leaf-galls of Zylenchus sp.? They are very inconspicuous, 
and consist of a spot in the leaf, usually towards the margin, about 
2 to 4mm. across, irregular in outline, about twice as thick as a 
healthy leaf, hence slightly prominent on both surfaces ; differing 
but little in aspect from rest of leaf, except in being slightly paler, 
or sometimes reddish-brown. 
The differences brought about by the gall-makers can be under- 
stood only by a comparison with a healthy leaf in section. The 
latter shows, from above downwards, the epiderm, then two or 
three layers of rather closely packed palissade cells, elongated at 
right angles to the surface, then two or three layers of irregularly 
branched cells, elongated in directions nearly parallel to the 
surface, and showing large intercellular spaces among them. 
Among these cells lie the fidrovascular bundles, usually close 
below the palissade layers. Then comes the lower epiderm, 
bearing numerous and variable branched hairs. 
In the galls the loose mesophyll below the palissade layers 
seems to be the first part attacked. The cells become less 
regular in form, and lie with the long axis in any direction, and 
are separated by wider interspaces. The next cells attacked are 
the lower palissades, and the upper palissades soon follow, the 
cells all resembling those of the loose mesophyll, without differen- 
tiation of the tissues as in the healthy leaf. Neither epiderm nor 
fibrovascular bundles undergo any noticeable change in structure. 
The interspaces were well filled in August with eggs and young 
worms ; but neither males nor females could be found, hence 
there may be a doubt as to the maker of the gall being a Zy/enchus. 
These galls are common on the Links near Aberdeen, bnt I have 
