39° DIVISION I1I.—MODE OF LIFE OF THE FUNGI. 
it developes and form a multitude of gonidia on it. These gonidia cannot attack 
plants when once they have lost their cotyledons. Hence when a number of these 
plants are growing together, some are often found thickly covered with Cystopus 
and surrounded by others of the same age which are quite untouched by the 
Fungus. 
Endophyllum Sempervivi makes its way in spring into any leaf of the host, 
spreads through all parts of the plant and produces its aecidia in the succeeding 
spring in the younger of the leaves which have lived through the winter, and may 
then persist for years in the same state of diffusion in a rosette of leaves, forming 
fresh aecidia every spring. The spot where Endophyll m Euphorbiae enters its host 
has been mentioned on page 364 ; the mycelium spreads from there through the entire 
plant and produces aecidia in the young leaves of the next year, producing deformities 
in their petioles. Melampsora Géppertiana penetrates in summer into the shoots of 
Vaccinium Vitis-Idaea, and its mycelium spreads through the parenchyma but does 
not deform it. After the succeeding spring it enters every year into the new terminal 
and lateral branches from the infected shoot, causing peculiar deformities in them, 
and forms its teleutospores not in the epidermis of the leaves but in that of the stem’. 
Kiihn and R. Wolff have shown that the germs from the sporidia of many 
Ustilagineae which attack grasses penetrate into the host when it is young and 
germinating, sometimes into the first sheathing leaf, sometimes into the lowest node 
of the young stem and even into the base of the young roots. The mycelium then 
grows with the growing stem and its lateral shoots, and at length makes its way into 
the organs in which the Fungus prefers to produce its sporophores, and consumes 
them and forms its spores. The mycelium which has grown with the growing internodes 
is not entirely destroyed when the elongation is completed; intercellular branches are 
preserved in the nodes, and these send new branches into the axillary buds which 
may be produced at the nodes, to repeat the process of growth already described. 
We are acquainted with a number of endophytic parasites, which so far resemble 
those last described in their behaviour, that their mycelium spreads through large 
portions of the host and then produces its sporophores in or at certain spots, and 
this may happen once only, or is repeated every year from the perennial mycelium in 
new branches and leaves, &c. Though the act of entering the host has not been 
observed in these cases, there can be no doubt that the circumstances are quite or 
nearly the same as those which are certainly known either in Endophyllum, or 
in’ the Ustilagineae which have just been described. Among these forms are most 
of the remaining Ustilagineae, the Aecidium of Euphorbia Cyparissias, the Peridermium 
elatinum of the ‘witches’ brooms’ of Abies pectinata, the Exoasci which also form 
‘witches’ brooms,’ Peronospora Radii of Pyrethrum inodorum and Peronospora 
violacea, Brk. of Knautia arvensis which produce spores only in the flowers of the host, 
Epichloe typhina which lives on the Gramineae and many others. 
Species in which the segments of their development differ from one another and 
stand to one another in the relation of alternate generations spread in the host in the 
same or in a different manner in the different segments. The first is the case for 
example in the Uredineae which have been already adduced as examples of narrow 

! Hartig, Lehrbuch d. Baumkrankheiten, p. 56. 
