436 SOIL FUNGI 



completely, with carbon dioxide as the only waste product. 

 Moreover a considerable proportion of the carbon in cellulose 

 may be reassimilated by the fungus in building protoplasm. This 

 observation on the utilization of carbon dioxide is elaborated by 

 Foster et al. ( 1941) in their recent studies on this subject. 



Abundant evidence, some of which is summarized in Chapter 3, 

 has been secured that many Basidiomycetes, especially wood- 

 rotting species, are capable of utilizing cellulose. Phycomycetes 

 are generallv regarded as incapable of digesting cellulose. The 

 work of Whiffen (1941), however, shows that certain chytrids 

 possess this ability. 



Manv fungi are known to be capable of utilizing starch. Among 

 22 species of soil fungi tested by Waksman (1916) for diastatic 

 abilitv, 6 proved capable of using starch. The Mucorales have 

 been shown to utilize manv monosaccharides, disaccharides, and 



also pectins. 



Decomposition of proteins. That fungi differ in ability to use 

 elemental nitrogen and nitrogen complexes was given considera- 

 tion in Chapter 2, where it was pointed out that some few species 

 can assimilate atmospheric nitrogen but that most of them prefer 

 amino acids, nitrate nitrogen, or else ammonium salts. That soil 

 funoi have the power of ammonifying proteins was first demon- 

 strated in 1893 by Miintz and Coudon (1893), using Mucor race- 

 mosus and Fusarium miitzii, and by Marchal (1893), using As- 

 pergillus terricola and Cephalothechtm roseum. Numerous in- 

 vestigations of this problem followed, including those of McLean 

 and \vilson (1914), Waksman (1916), and Henkelekian and 

 Waksman (1925). 



McLean and W T ilson (1914) employed members of the Mucor- 

 aceae, Aspergillaceae, Dematiaceae, and Moniliaceae, finding that 

 all could produce ammonia either from dried blood or from cot- 

 tonseed meal. It was observed that some species are more active 

 than others, but of much more interest was the finding that soil 

 fungi exceed bacteria in ammonifying power. Waksman (1916) 

 showed that Trichoderma koningii is an especially potent ammoni- 

 fier. Evidence is lacking that any species of soil fungi takes part 

 in nitrification. 



Henkelekian and Waksman (1925) observed a direct correla- 

 tion between the amount of nitrogen transformed into ammonia 



