39 



DIVISION III. 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 Goppertiana 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 1 . 



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. 



