70 
Rev. T. A. Jefferies. 
aerial stems in the districts where this work has been carried on, and 
have since been found on examination to be common in several 
widely scattered areas. The development of the gall occasionally 
produces a curious looping of the haulm and some of the leaf 
sheaths surrounding it (Fig. 1, g-s.), but more commonly the 
swelling is concentric and does not deflect the stem (opposite g.s.). 
Sometimes the insect affects the stem before the basal internode 
has elongated, when the gall is produced at the base, instead of 
above the “ joint,” and looks very like the ordinary tuberous basal 
internode (g-b.). In this case, however, the inflorescence, its axis, 
and one or more leaves may be suppressed (above g-b.), and the 
basal internode does not elongate and swell to form a storage organ, 
the food reserve being deposited in the leaf sheaths around the 
nest of larvae and in the subjacent cord roots instead of in the stem* 
From the presence of the larvae between the stem and leaf-sheaths, 
whose blades had not opened when the check to stem development 
took place, it may perhaps be inferred that the eggs are deposited 
by the fly in the position in which the nests are found, an inference 
which is supported by the facts that young galls frequently show a 
puncture and that the female insect possesses an ovipositor. 
Apart from these early attacks, which are quite exceptional, no 
harm seems to be done to the plant. During the season the larvae 
develop into pupae and the galls increase in size to accommodate 
them. The mature insects emerge on the Pennines about the end 
of May. 
V. Conclusion.. 
The inflorescence, flower, and fruit of Molinia have already 
been described by systematic and other writers, and my own 
investigations concerning them and the embryology and develop¬ 
ment are not yet complete. I have therefore limited this paper to 
the structure of the vegetative organs, the special points in which 
may now be summarised. 
1. Among the peculiar features emphasis may be put upon 
(a) the unusual distribution of the root hairs, ( b) the prominent 
endodermis of the cord roots, ( c) the structure of the basal inter¬ 
nodes and the nature of the food reserves they contain, (cl) the 
absciss layers for the protection of the more lasting members, and 
(e) the vascular bundles of the leaves with their thick walls, double 
sheaths, and stereome girders. 
2. Attention should be called also to such general features as 
(a) the wealth of mechanical strengthening tissue in all parts of the 
plant, (b) the remarkable development of xylem elements, ( c) the 
