CONDITIONS OF LIFE OF THE MOULD FUNGI. 515 



is not till development has reached a certain stage that 

 the above-mentioned nutrient materials hecome necessary. 

 Hence the sprouting of moistened spores can be observed 

 even on glass plates. In the case of some fungi how- 

 ever, for example Mucor mucedo, it is true that the first 

 sprouting can only occur on suitable soil. Besides 

 water the presence of oxygen and a suitable tempera- 

 ture are also necessary for the process of germination. 

 Here also the minimum, optimum, and maximum of 

 the temperature differ in the case of different species of 

 fungi. In the case of penicillium spores the former is 

 about +0'5 C., the latter about +43 C., and the 

 optimum about +22 C.; in the case of Aspergillus 

 fumigatus, on the other hand, the minimum, according 

 to Lichtheim, is 15 C. The presence of light is not 

 necessary for the germination of the spores of the fungi. 

 Between the point when the conditions necessary for 

 germination come into play and the formation of a germi- 

 nating tube a certain period of time is necessary, the length 

 of which is dependent on the species of spore, and pro- 

 bably, above all, on the thickness of the spore membrane, 

 and varies from a few hours to several days. Similar 

 variations also exist with regard to the duration of the 

 vitality of the spores. In the case of the uredo and Duration of 



.-,. P., /.. .11 .1 the vitality of 



aecidium spores or the rust iiingi, as well as in the the spores. 

 case of peronosporeae, the duration of vitality is only 

 a few weeks, while the spores of Penicillium glaucum 

 are able to sprout after a year and a half, those of 

 Aspergillus niger after more than a year, those of 

 Mucor stolonifer after a year, of Aspergillus flavus 

 after six 3*ears, of Aspergillus fumigatus after ten years, 

 and of Tilletia caries and Ustilago carbo after about 

 eight years.* There is a further peculiarity in con- 

 nection with the spores, namely, that they are only 

 able to sprout after a considerable period of rest. 



* Quoted from de Bary. 



