EXTIUE SHOOTS AFFECTED BY FUNGI. 525 



&c., fall off the trees at the end of May. They are eaten in many districts, but 

 have an insipid, sweetish taste. 



Galls consisting of whole shoots, both the stem and its leaves being altered by the 

 parasite, are found principally on trees and shrubs, and only rarely on herbaceous 

 plants. Examples of the latter, however, are furnished by the metamorphosed 

 shoots of the Shepherd's Purse (Gapsella Bursa -pastoris) produced by Gystopus 

 cavdidus and Peronospora parasitica. Here the leaves, especially the floral-leaves, 

 as well as the ground-tissue of the stem undergo pronounced hypertrophy. The 

 petals, which measure only 2 mm. in length in a healthy plant, may become even 

 15 mm. long; the sepals also elongate, become fleshy and brittle, and are distorted 

 and crumpled in all manner of ways. Only six stamens are developed in normal 

 flowers, but in hypertrophied specimens there are often eight. The metamorphosis 

 produced by Uromyces Pisi in one of the Spurges, Euphorbia Gyparissias, is even 

 more remarkable. The stem elongates far beyond its usual dimensions, and the 

 leaves, which are crowded together on normal shoots, are thus separated by con- 

 siderable intervals. The distance between two adjoining successive leaves in the 

 healthy Euphorbia Gyparissias is only 0'5 mm., but in the hypertrophied specimens 

 it becomes 2-3 mm. Infected shoots on an average are twice as high as healthy 

 ones. The foliage-leaves, which are thin, flexible, linear, and twelve times as long 

 as they are broad in the healthy plant, become, in the infected specimens, thick, 

 brittle, elliptical, and only 2-3 times as long as they are broad. The bluish-green 

 colour of the normal plant is changed into a yellow-ochre tint, and this contributes 

 not a little to the odd appearance of the plant. Affected plants are not uncommon 

 in Switzerland; a locality in which this disease has been very prevalent in recent 

 years being Saas-Fee in the Saas-thal. The metamorphoses produced on the shoots 

 of Periwinkles (Vinca herbacea, major, and minor) by the Uredospore-stage of 

 Puccinia Vincae and on shoots of Cirsium arvense by the Teleutospore-stage of 

 Puccinia suaveolens are very Like those of the Euphorbia just mentioned, since 

 the stem becomes much elongated and the leaves shorter, broader, yellow, and brittle. 

 When flowers are developed on these affected shoots, they are more or less abortive 

 and sickly, and no fruits or fertile seeds arise therefrom. Frequently the shoots 

 blossom prematurely. For example, we can at once detect by its elongated rosette- 

 leaves when Primula Glusiana and minima are infected by Uromyces PrimulcB 

 integrifolice, and it may be observed when this is the case that the shoots do not 

 wait until the next spring to develop the flowers laid down in the summer, as usual, 

 but open them in the autumn of the same year instead. 



The Cowberry (Vaccinium Vitis-Idoea) is especially worthy of notice among 

 iow woody plants, because two kinds of parasite attack its shoots. Melampsora 

 Gceppertiana, in the Teleutospore-stage, causes a marked, gouty thickening in the 

 cortical parenchyma, which is converted into a spongy tissue; at first it is flesh- 

 coloured, but soon assumes a chestnut-brown tint. The stems elongate very much 

 and grow vertically upwards; and when several of them close together are thus 

 attacked they present a besom -like appearance. The foliage-leaves are much 



