Ward, — Recent Researches on the Parasitism of Fungi. 9 
Wound-parasites. Sub-cultures. Facultative and obligate parasitism. 
Saprophyte. Incubation-period. Symbiosis. Stomatal infection. Abio- 
genesis. Cuticular infection. Fermentation. Predisposition. Enzyme. 
Capacity of infection. Prototrophic, metatrophic, and autotrophic. 
Haustoria. Appressorium. Pleomorphism. Inoculation. Chemotaxis. 
Positive and negative chemotropism. Infection vesicle. Adaptability. 
Intra- and inter-cellular mycelium. My coplasm. Pleophagism. Mycorhiza. 
Endo- and exo-trophic. Lipoxeny. 
Uredineae. 
It is now time to pay some regard to the practical limits of my subject, 
imposed alike by the time at command, and by the patience of my hearers. 
It would be quite impossible in this address to cover the whole of the 
ground implied in the parasitism of the Fungi, and I therefore propose to 
deal more especially with the group in which the most important victories 
in our struggles for new knowledge of parasitism have been won. This 
group is the Uredineae, a group which has become especially interesting, 
not only on account of the great tax its ravages have imposed on our corn 
and other cereal crops, but because it is the focus of the classic work done 
by De Bary, referred to above, and of the important discoveries since 
made, matters which I propose to deal with below. 
Heteroecism. 
Almost simultaneously with De Bary’s classical researches (9) on 
Puccinia graminiSyP ' 1 Rubigo-veral and P. ‘ coronata] in 1864-5, where he 
showed that the latter is heteroecious on Rhamnus^ as is the former on 
Berberis, Oersted (123) proved that the so-called Roestelia on Pomaceae is 
merely the aecidium-form of the Gymno sporangia of Junipers. 
Thereupon followed a period of busy seeking after alternate hosts, 
with such success that by 1870 as many as seven, and by 1880 fourteen 
well-established cases had been accepted, chiefly the results of investigations 
by Magnus (106), 1874, Schroter (156), 1875, Wolff (205), 1874 and 1877, 
Rostrup (143), 1874, Winter (202), 1874-5, Nielsen (121), 1877, Reichardt 
(141), 1877, and De Bary (9) : of these the most interesting was probably 
Wolffs demonstration that Peridermium Pini was merely the aecidium of 
Coleosporium Senecionis. 
By 1890 the number of cases of heteroecism had amounted to fifty, of 
which Hartig’s (78) work on Calyptospora deserves to be especially men- 
tioned : you will remember that the remarkable Calyptospora Goeppertianum 
on Vaccinium was here shown to be the puccinia-form of Aecidium colum- 
nare of the Silver Fir. 
The number of demonstrated cases of heteroecism now known is about 
