CHAPTER VI. — PHENOMENA OF GERMINATION. 345 



Coleosporium, Leptochiysomyxa, Chrysomyxa, Cronartium, Hemileia, and others, in 

 which the teleutospores belong to the first category, — the megalogonidia or resting 

 gonidia of Hypomyces and its allied forms, some spores of the Ustilagineae and 

 some others. 



The period of rest in many of these cases is observed to last for a fixed time, 

 and to coincide with certain periods of vegetation and seasons of the year. The 

 teleutospores, for instance, of the Uredineae, the most frequent representative of 

 which is Puccinia graminis, are dormant during the winter. The teleutospores of 

 Puccinia ripen at the end of summer and during the autumn and germinate under 

 favourable conditions in the following spring, and it is difficult to procure their 

 germination before that time even under cultivation. This appears also to be the 

 history of the oospores of the Peronosporeae which do not live in water, and of the 

 resting-spores of Protomyces macrosporus and some species of Synchytrium, S. 

 Anemones for instance and S. aureum, &c. (see page 167), which all ripen in the 

 summer and do not germinate till the next spring, and in their case also it is found 

 difficult to shorten the resting period in plants under cultivation. 



It is different, according to Woronin \ with the resting-spores of Tuburcinia 

 Trientalis among the Ustilagineae and of Sorosporium Saponariae, which ripen in 

 the course of the summer and are not capable of germination before the end of 

 September of the same year. 



This coincidence with a fixed period of the year is at least not a general rule in 

 the zygospores of the Zygomycetes, in the oospores of many Saprolegnieae 2 (the 

 Pythieae), and in the resting-spores of Synchytrium Taraxaci, though it may occur 

 in some cases (Sporodinia, Synchytrium). In the absence of this coincidence we 

 can only speak of a necessary period of rest which lasts some weeks or months and 

 varies in different species and individuals. 



We have no exact observations on the maximum of the resting time possible 

 under favourable circumstances in the case of species which are not confined to fixed 

 seasons of the year. It may extend to a year and probably may exceed a year 

 in the spores of Pythium proliferum kept under water. Our knowledge of the 

 Zygomycetes and Saprolegnieae would lead us to suspect that, when the conditions 

 required for germination are excluded, the power of germination ceases at an 

 earlier period in them than in the more hardy forms, which retain their vitality more 

 than a year without being obliged to go through a period of rest. 



The forms in which the resting time coincides with fixed periods of the year 

 appear as a rule not to retain their powers beyond the favourable time for 

 germination which follows their maturity, or not to retain them long beyond that 

 time. Teleutospores of Puccinia graminis which have lasted during the winter 

 germinate with great readiness in the spring which succeeds their period of ripeness, 

 more slowly and more infrequently during the following summer months, and I was 

 unable to procure their germination after August or in the spring of the second year. 

 It is the same with other allied species. Woronin failed to make the spores of 

 Tuburcinia Trientalis germinate when they had remained without germinating from 



1 Beitr. V. See also before on page 180. 



2 See De Bary, Beitr. IV. 



