4 ECIDIA 
The oldest spores being at the top, they separate as soon as 
mature, and are blown away by the wind; fresh spores are 
produced for a time from below. Since these cups are in dense 
clusters over the whole of the affected spot, they are known as 
“Cluster-cups.” The mycelium in the leaf continues to develop, 
and the spot enlarges and ceases to be round. But the swelling 
of the tissues within which the mycelium is living can be 
carried to such an extent as to distort and curl the leaf, much 
in the same way that Hxoascus deformans (the Peach Leaf-curl) 
affects the Peach leaves. The epidermis above and around the 
spot, also, often becomes coloured red or purple by an anthocyan- 
derivative, both these effects being a response by the leaf-cells 
to the stimulus of the parasitic growth, and perhaps part of an 
effort to throw off or checkmate the invader. The mycelium, 
moreover, is not confined ‘to the leaves; it may originate in 
the petiole, in the stipules and in the stem. In the latter case 
it causes notable curvature and distortion; an instance is 
recorded where the curved gall-like mass, formed on the stem, 
measured as much as 10 cm.‘in length, and similar but smaller 
growths may frequently be met with. 
Here should be noticed the close parallelism, up to a certain 
point, in the formation of the spermogones and the ecidia— 
they have similar shapes, they are both enclosed by a layer of 
sterile hyphex, they arise in (usually) quick succession on the 
same mycelium, they give off basipetal chains of spores frgm 
their base. On the other hand, besides the difference any the 
nuclei, the xcidiospores differ from the spermatia in their larger 
size, In possessing a large store of reserve food, in their capacity 
for germination, and for producing infection in another plant. 
THE AICIDIOSPORES. 
The mode in which the ecidiospores are produced is as 
follows:—The upper cell of the sporiferous hypha usually 
divides into two, an upper sterile cell, and a lower fertile or 
basal cell, each with one nucleus. -The upper cell disintegrates 
and perishes; the lower fertile cells conjugate with one another 
in pairs, the process consisting in the formation of a small hole 
