368 DIVISION IIL—MODE OF LIFE OF THE FUNGI. 
Carbo, Claviceps, and many others) belong 'to the same category, together with all 
those thatlive on animals, unless we choose to reckon the phenomena ofinflammation, 
suppuration, and formation of tumours caused by.the presence of the Fungus 
in warm-blooded animals as cases of abnormal growth, a point which may for 
the present remain undecided. 
The occupation bythe deforming parasite is followed immediately byanomalous 
processes of growth in the host or in the parts of the host, the word anomalous being 
here understood to mean every condition different from that which is found in the 
plants or the parts not attacked by the Fungus. Countless examples of this class of 
parasites are to be found among those which live on plants. The phenomenon 
necessarily presupposes a power of growth in the parts to be deformed, and in the 
‚higher plants therefore it usually implies that they were attacked in the young state 
when their growth is still incomplete. 
The extremes of deformation, which pass, it is true, readily into one another, consist 
on the one hand inan abnormal increase of growth and abnormal enlargement of parts of 
the tissue, which are in other respects normal and normally disposed, and hence in the 
swelling of the individual cells, as in the case of epidermal cells which are occupied by 
Synchytrium and the adjoining cells, or else in a monstrous enlargement and inflation of 
entire members and aggregates of members in the higher plants, such as the swelling of 
the flower-stalks and the enlargement, often to an enormous size, of the flowers of the 
Cruciferae when attacked by Cystopus. These may be said to be cases of Aypertrophy. 
On the other hand the parts may be deformed with very slight or with no hypertrophy 
worth mentioning; such are well-known deformations of the shoots of herbaceous 
species of Euphorbia by Uromyces Pisi, U. scutellatus, and Endophyllium Euphorbiae, 
and the ‘witches’ brooms’ on the branches of the fir and cherry-tree when attacked by 
Peridermium elatinum or Exoascus. In the fir (Abies pectinata), for example, these 
branches grow vertically upwards, like small trees, from the horizontal limbs, with 
branches spreading in every direction, and leaves which spread in the same manner and 
fall off year by year, while the entire excrescence continues to grow for years‘. In the 
flowers of Knautia arvensis, when occupied by Peronospora violacea, the stamens often, 
though not always, acquire the characters of normal petals of a beautiful violet colour, 
and the blooms are filled by them. These phenomena of deformation by Fungi may 
be termed mycelogenelic metamorphosis. The processes in the formation of Lichens, to 
which we shall recur in a later page, have a considerable resemblance to them. 
Lastly, the new formation of members, such as are not seen in any form on the 
plant when free from the Fungus, are caused on parts of some of the higher plants by 
the presence of the Fungus. The most striking instances of the kind are the delicate 
round bodies of the size of a cherry which Exobasidium Vaccinii produces on the 
leaves of the alpine rose, and the excrescences on the stem of Laurus canariensis, L. 
caused by Exobasidium Lauri and described at length by Geyler *,—club-shaped for- 
mations with blunt edges, of the length of a finger, and branched like an antler, 
which Schacht even mistook for aerial roots. But the strangest example of the kind 
is found in the Saprolegnieae when attacked by Rozella, which will be described below. 

' Bot. Ztg. 1867, p. 237. 
? Bot.-Ztg. 1874, p. 321. 
