CHAPTER VI 

 HISTOLOGY AND CHEMISTRY OF FUNGI 



Histology. — Naked cells which are destitute of a cell wall and con- 

 sist of naked protoplasm occur as motile cells in only two unimportant 

 groups of the OOMYCETALES. The cell wall of fungi does not 

 appear from the results of numerous workers upon its chemistry 

 to be of the same nature in the different groups of them. A general 

 term which has been in current use and which was first suggested 

 by A. de Bary is that of fungous cellulose, but that term, as far 

 as indicating the chemic character of the membrane is concerned, is 

 a misnomer. It has its correct application, if we employ the term in 

 the sense of fungous membrane substance. We owe to C. van Wis- 

 selingh (1898) the examination of about a hundred species from nearly 

 all of the orders and most of the families of EUMYCETES. Wissehngh 

 could detect the presence of cellulose with certainty only in two families, 

 the Saprolegniace^ and the Peronosporace^. This carbohydrate 

 could not be detected either in the ZYGOMYCETALES or in any 

 of the MYCOMYCETES examined, and especially was it found to be 

 absent in the yeast Saccharomyces cerevisia. The researches of 

 Winterstein, Gilson and Wisselingh proved that chitin formerly sup- 

 posed to be of animal origin was found in the membranes of fungi. 

 With the exception of the two families mentioned above, the bacteria 

 and the yeasts, chitin has been detected in all other species of fungi 

 examined, e.g., Mucor mucedo, M. racemosus, Rhizopus nigricans, 

 Penicillinm glaucum, Trichothecium roseum, in the sclerotia of Botrytis 

 cinerea and Claviceps purpurea. We do not know at present of the 

 simultaneous occurrence of cellulose and chitin in the same cell wall. 

 E. Winterstein has found true hemicellulose in certain fungi and other 

 chemic substances have been reported such as carbohydrates of the 

 pentosan group, pectose, callose, etc. 



The outer layers of the wall, in some fungi (Tremellace^) may be 

 mucilaginous, so that it is resolved into a soft gelatinous mass. Lignifi- 

 cation has been reported in the large pileated fungi though whether 



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