346 DIVISION III. MODE OF LIFE OF THE FUNGI. 



the time of their maturity till the late autumn ; and it would appear, from the 

 observations which we possess, that the regularly hibernating oospores of the 

 Peronosporeae and the winter-spores of the Chytridieae, &c. behave in a similar 

 manner, though no exact researches have been made into the possible maximum 

 duration of their resting time. 



The power possessed by the spores of Fungi of withstanding the effects of 

 injuries caused by agencies from without varies very much in individual cases. 

 Disregarding the effect of poisonous bodies, we have to consider under this head the 

 withdrawal of water, extreme temperatures, and mechanical attacks. 



As regards mechanical injury, Van Tieghem 1 found that some ripe spores gonidia 

 of Phycomyces, Pilobolus oedipus, Mortierella reticulata, and zygospores of Sporodinia 

 and Mucor fusiger when they are wounded or cut into not too small pieces, have 

 the power of healing the surfaces of the wound by forming a new protoplasmic 

 pellicle and a new membrane, or, if the lesion is slight and partial, they can divide 

 into daughter-cells, and each of these cells and each of the cicatrised fragments 

 continues or becomes capable of germination if the circumstances are favourable. 



Some spores are very sensitive to the withdrawal of their water which is effected 

 by drying them in moderately warm air (20-22 C). This is the case with swarm- 

 spores developing beneath the water as well as the gonidia abscised in the 

 Peronosporeae mentioned above, and with the short-lived spores of the Uredineae. 

 The example of Phytophthora infestans shows that these spores lose their powers of 

 germination quickly in the air-dry state even after a period of 24 hours. It would 

 appear also that the oospores of the Saprolegnieae which ripen under water cannot 

 bear being dried in the air at an ordinary temperature. It is estimated that at least 

 95 per cent, of the ripe ejected spores of Sclerotinia ciborioides lose their power of 

 germination if they are kept dry in the air on glass plates for 1 2 days in a temperature 

 of about 20 C. 



Occasional observations seem to show that the spores of many Lichen-fungi are 

 among those which will not bear desiccation, but the point requires more thorough 

 investigation. 



It is evident that the spores which we have been describing form a very small 

 part of the whole number ; the great majority of the spores of Fungi retain their 

 power of germination for a long time in the air-dry state. Some display great power 

 of resisting high temperatures and must therefore be able to bear the artificial 

 extraction of a large proportion of the water which they contain. 



Resistance to extreme temperatures is shown more especially in relation to a 

 high degree of cold. The spores which were recently spoken of as regularly 

 hybernating in our temperate climates will endure a cold of 15 to 25 C. without 

 having their power of germination in the least affected. This experience justifies 

 us in assuming the same or a similar power in the majority of the other long-lived 

 spores mentioned above. This was confirmed by Hoffmann in the case of Ustilago 

 Carbo and U. destruens, Trichothecium roseum, Fusarium heterosporum, Penicillium 

 glaucum, Botrytis cinerea, and by Schiridler 2 in that of Tilletia Caries. 



1 Ann. d. sc. nat. ser. 6, IV, p. 315. 



2 Wollny's Forschungen a. d. Agriculturphysik, III, p. 288. 



