On Teleutospore Germination. i i 
When, however, one compares the various published figures of 
teleutospore germination (e.g. those of Tulasne, De Bary, Plowright 
and Sappin-Trouffy), it is clear that the limit of growth is apparently 
very different in different cases. In some the promycelium is of 
very considerable length, and only the apical portion has become 
divided into the sporidia bearing-cells, the lower portion being 
merely an empty hollow tube (cf., the figures of Sachs and 
Tulasne for Puccinia gram inis, reproduced in most text-books; 
Gymnosporangium, Tulasne, pi. x., fig. 7; Triphragmium , Plowright, 
pi. iv., fig. 6.) In other cases the promycelium is exceedingly short, 
so that it is reduced to little or nothing more than the four charac¬ 
teristic cells (cf. Puccinia graminis, Massee, fig. 65; Phragmidium 
rubi , Tulasne, pi. ix., fig. 15, Plowright, pi. iv.. fig. 8; Sappin- 
Trouffy, fig. 50; Gymnosporangium, Tulasne, pi. x\, fig. 6; 
Cronartium, Tulasne, pi. xi., figs. 16-18.) 
If the differences in length of the promycelium were confined 
to teleutospores of different species they might be accounted 
for by specific differences of development ; but variations in the 
length of the promycelium quite as great are to observed in the 
teleutospores of one and the same species (cf. the figures of 
Puccinia graminis and Gymnosporangium mentioned above), and 
even in the individual cells of a single compound teleutospore (cf. 
Plowright, pi. iv., fig. 6.) Variations such as these can only be 
explained as a result either of varying external conditions, or of 
individual spore (or cell) differences. 
The external conditions necessary for the germination of the 
telentospores and for sporidia formation are, as is well known, 
moisture, and a certain degree of temperature. According to most 
observers the moisture can be supplied either in the form of water 
or of damp air ; but, apart from this, there is very little knowledge 
as to the exact conditions necessary for the two processes. 
In the spring of last year some observations were made on 
the germination of teleutospores of Uromyces fabae , De Bary, 
Puccinia graminis, Pers, and Phragmidium rubi, Wint. (the teleu¬ 
tospores of all three requiring a winter's rest before germination), 
which show that sporidia formation must be sharply distinguished 
from termination in relation to external conditions, and that the 
variation in length of the promycelium is due to the varying 
action of a definite external factor. 
The spores were sown partly in hanging drops, and in part 
over water in Petri dishes so that the spores themselves were 
