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 mutatis 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 modifications 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 OP 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 1 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 Ustilago Carbo germinates according to Hoffmann at a 

 temperature of from +0.5 to i° C, Botrytis cinerea at + i.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 well 

 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 2 , 

 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 +I5°C. 



1 Sitzgsber. d. Wiener Acad. 67, I (1873). 



2 Berliner klinische Wochenschrift, 1SS2, Nr. 9. 



