SPORE GERMINATION 



363 



distilled water and in dextrose solution lacking minerals (Lin, 1945). 

 From his experiments involving various inorganic compounds, Lin 

 concluded that carbon, magnesium, nitrogen, and phosphorus, are 

 required (Table 60). The need for sulfur was not so evident as that for 

 the other elements, and sulfur was not essential. The minimum require- 

 ments of nitrogen and phosphorus were calculated to be of the order of 

 10"' Mg per spore. No evidence was found that an external supply 

 of any organic substance, other than sugar, is necessary for spore 

 germination. 



Table 60. The Essentiality of Various Ions for the Germination of the 



CoNiDiA OF GlomereUa cingulata 

 (Lin, Am. Jour. Botany 32, 1945.) 



* In all cases, the concentration of glucose is 0.01 per cent, that of each of the mineral salts 1.0 milli- 

 mole. 



The constituents of the medium may modify the effects of pH on spore 

 germination. This is illustrated in Fig. 75 by the germination of Lenzites 

 saepiaria on 2 per cent bacto-peptone, in sucrose-nitrate (Czapek's) 

 solution, and in beet decoction (Webb, 1921). 



Emerson (1948) showed that D-xylose as a carbon source gave a high 

 percentage of germination of ascospores of Neurospora crassa without 

 heat treatment. Xylose was more effective when autoclaved than when 

 filtered. This was believed to be due to the slight conversion to furfural, 

 which was also shown to be active in increasing spore germination. 



From this brief discussion it is evident that little is known about the 

 effects of nutrition upon spore germination. This is no doubt due, in 

 part, to the lack of planned experimental work along this line. Many 

 of the favorable effects of natural products may in fact be due to the 

 presence of stimulants rather than to the nutrients. At the present time 

 we have no conclusive evidence that spores require an external source of 

 vitamins for germination. In the light of the recent discovery of Ryan 



