CHAPTER VI. —PHENOMENA OF GERMINATION. 349 
mature, this condition for their development is almost entirely wanting, and the 
height of summer which follows upon their regular time of germination is equally 
unfavourable; the phenomena connected with their powers of germination are 
closely accommodated to these circumstances. The teleutospores of this Fungus. 
are at the same time the only means, or if we take some doubtful and exceptional 
cases into consideration almost the only means, by which the plant lives through the 
winter in these latitudes, for all the other organs die as a rule at the beginning of 
winter. Exactly similar conditions prevail mulatis mutandis in the case of the 
spores which normally live through the winter, of other Uredineae, of Protomyces, 
Synchytrium, and the Peronosporeae, of Cystopus Portulacae in a remarkably 
striking manner in Germany, of Tuburcinia Trientalis and some others. 
These cases of exact adaptation to the function of hibernation are connected 
with a long series of other cases within the affinity of the forms mentioned in which the 
above characters in the spores are subject to very manifold madifications to meet new 
adaptations in the life-conditions of the plants. Thus, for instance, in the alliance of 
Puccinia graminis we come to the Leptopuccinieae with a mycelium which lives through 
the winter, and spores which are usually short-lived and germinate as soon as they are. 
ripe, and still further to the Chrysomyxae with a mycelium which also lives through 
the winter, and a copious supply of spores which are all short-lived and can ger- 
minate only in the summer in which they are formed (see sections LXXXII, CX). 
Similar cases occur everywhere in other groups. 
2, EXTERNAL CONDITIONS OF GERMINATION. 
Section XCVI. The external conditions necessary for the commencement of 
germination in the spore are in general the same as are required for the germs and 
seeds of other plants; a certain temperature of the environment, a supply of oxygen and 
water, and in some cases also of nutrient substances. 
The cardinal points in the germination-temperature of spores have been exactly 
ascertained for a few Fungi only. Wiesner found the minimum to be from 1.5° to 
2° C. in the gonidia of Penicillium glaucum, the maximum 40° to 43° C., and the 
optimum about 22” C.; the cardinal points are probably similarly situated in very many 
Fungi in our latitudes. Thus Ustilage Carbo germinates according to Hoffmann at a 
temperature of from +0.5 to 1° C,, Botrytis cinerea at +1. 6° C., Ustilago destruens 
requires a temperature above +6° C, but continues to germinate at 38.75° C.; 
I observed Cystopus candidus develope zoospores and their germ-tubes as weil 
at +5 as at 25°C. 
More exact observations will bring to light many variations in this respect in 
species and individuals such as are found in other regions of the vegetable 
kingdom. Aspergillus fumigatus, Fresen., which was carefully examined by Lichtheim?, 
may be mentioned as a striking instance of this kind among the Fungi; in this 
plant it was approximatively determined that the minimum did not fall much 
below +15°C. 

1 Sitzgsber. d. Wiener Acad. 67, I (1873). 
? Berliner klinische Wochenschrift, 1882, Nr. 9. 
