392 DIVISION III.—MODE OF LIFE OF THE FUNGI. 
of a foliage-leaf which stands underneath an inflorescence, generally the next but one 
or two beneath it; the leaf or leaves above it and the inflorescence itself wither away in 
consequence. 
In this and in almost all the cases of the Peronosporeae and Ustilagineae 
which have been mentioned the mycelium spreads through the entire stem 
of the plant but cannot be seen in it, and causes no change in it which is visible 
from without. A superficial examination only would lead us to suppose that only 
the parts chosen for the formation of spores are occupied by the Fungus, and that 
the rest of the plant which looks quite healthy is free from it, But in most cases of 
the kind all or nearly all the similar parts of a plant where spores are formed by 
preference are seen even in their young state to be uniformly occupied by the spore- 
forming organs of the Fungus. This enables us to conclude in doubtful cases that 
the Fungus is one which is widely spread and not confined to a limited spot, because 
in the latter case it scarcely ever happens, for obvious reasons, that all similar young 
parts are attacked in this uniform manner. 
Secrion CXII. Independently of these coarser phenomena of localisation 
the histological distribution, as we may briefly term the behaviour of the Fungus 
to the cells and tissues of the host, is also liable to variations in endophytic 
parasites on plants and in the endophytic haustoria of parasites which are otherwise 
epiphytic. In considering these variations we must of course also keep in view the 
reactive influence of the host, which is necessarily connected with them. 
In the higher plants. with their various kinds of tissue the wood-destroying 
Fungi described at page 383 spread in the tracheal and sclerenchymatous tissues and 
destroy them. But most parasites exclusively or almost exclusively affack living cells 
containing protoplasm, the parenchyma therefore, soft bast and epidermis, where the 
tissues are differentiated, and even the wood-destroying Fungi just named do the 
same. Accordingly a number of histological localisations result from conditions such 
as have been already described, and further details must be sought in special treatises 
on the subject. But as a topic of general interest we must briefly notice the 
differences in the behaviour of endophytic parasites to the living cell. 
In unicellular hosts an endophyte is necessarily zu/racellular, that is, vegetates 
inside the cell. It may also be intracellular in pluricellular tissues, but it may also 
spread in the zufercellular spaces, or it may exhibit both modes of distribution. When 
its growth is intercellular, it stands of course in the relation of an epiphyte to the 
individual cell, and of that we need say no more here. The entry of the parasite 
into the cell of the plant or into parts of it takes place in very dissimilar forms and 
with very. dissimilar consequences. 
To begin with the extreme which lies nearest to the superficial view of the 
subject, there are many parasites wkose hyphae penetrate through the membrane 
and into the protoplasmic body of the cell, and kill and destroy the latter at once; 
examples of such Fungi are seen in all the facultative parasites described above, 
Sclerotinia and Pythium and their near allies the Phytophthoreae and others; 
Ancylistes is an instance of this in unicellular plants (page 139). 
Other parasites also penetrate the membrane of the cells and pass through 
them and through the protoplasmic body. But the latter does not at first succumb to 
the assault of the parasite, but retains the qualities which it has in the living cell, and is 
