io Ward . — Recent Researches on the Parasitism of Fungi. 
150, of which the long and hitherto vain search for the alternate form and 
host of Aecidium Elatinum , the Fungus of the Witches’ Broom of the 
Silver Fir, and which Fischer ( 69 ), 1902, has shown to be Melampsorella 
Caryophyllacearum , is surely the most interesting. 
But another interesting aspect of this fascinating theme was the dis- 
covery that heteroecism is not confined to the Uredineae, for Nawaschin 
and Woronin ( 117 ), 1896, have shown that Sclerotinia heteroica> an Ascorny- 
cete, alternates between Ledum and Vaccinium. 
Equally interesting is the result that several animal parasites, especially 
certain Vermes, Arthropoda, and Protozoa, are heteroecious on two or even 
three hosts. An interesting example is that of the insects producing Galls 
on the Spruce and Larch ; but as Mr. Burdon, who has for some time been 
working at this subject in our laboratory, will give you an account of these 
phenomena, I pass them by with this reference. 
Cycle of Life-History, and Classification. 
Most species of Uromyces , Puccinia , Melampsora , Pucciniastrum , &c., 
form teleutospores which germinate only after resting through the winter, 
and are heteroecious ; but there are many cases — e. g. Endophyllum , Puc- 
cinia Asparagi , P. malvacearum , Uromyces append icuiatns, &c. — where these 
spores germinate during the summer or autumn of their development 
and are autoecious. 
Moreover .Endophyllum and others only form teleutospores, and have a 
perennial mycelium. A perennial mycelium also occurs in Gy mno sporangium 
and others. 
In the cases of Chrysomyxa Rhododendri and C. Ledi , again, we find 
that the mycelium remains alive in the leaves throughout the winter, and 
develops teleutospores in the spring, and these germinate forthwith. 
In Cronartium and Coleosporitim , on the other hand, it is the aecidial 
mycelium which is thus perennial ; while in Melampsorella both the 
teleutospore- and the aecidium-mycelia are perennial. 
An important step forward, after the discovery of heteroecism, was 
made by Schroter in 1879 ( 155 ), in proposing as a basis of classification 
within the genera Puccinia , Uromyces , &c., the sequence of spores and their 
behaviour. Schroter suggested that the various groups should be put into 
sections according to the existence of aecidia or not, according as they 
were heteroecious or autoecious, and according to the behaviour of the 
teleutospores, &c. 
Taking, for example, Puccinia as the largest and best worked genus, 
Schroter denominates the aecidial-form I; the uredo-form II ; and the 
teleutospore-form III ; and groups as follows : — - 
