An electron microscopic and X-ray analysis of the walls of selected lower Phycomycetes

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Abstract
The cell walls of Chytridium sp., Rhizophydium sphaerotheca, Allomyces macrogynus, Monoblepharella mexicana and Gonopodya sp. have been examined by electron microscopy and X-ray diffraction analysis. Wall material was obtained by a permanganate oxidation procedure. In all cases, except one, the X-ray diagrams showed only chitin reflexions. The exception, the walls of Rhizophydium, gave an unexplained reflexion corresponding to a spacing of 12$\cdot $8 angstrom. The detection of chitin in the walls of Monoblepharella is a noteworthy observation, since some mycologists have believed that cellulosic cell walls are a characteristic of the order in which this genus is placed. With all five genera, an appropriate test showed that cellulose could be present only in trace amounts, if present at all. The electron micrographs of the walls of all the fungi studied showed that the chitin was usually present in the form of long microfibrils, 150 to 250 angstrom in width. In some instances, however, short fibril aggregates appeared. It is believed that this form of chitin originated through chemical modification during treatment. Unlike the cell walls of the other genera, the walls of Gonopodya were modified appreciably by dilute hydrochloric acid. It is recognized, however, that this difference may be a consequence of the alkaline digestion procedure used in the initial separation of the walls from other hyphal constituents. It can be concluded that the cell walls of these five genera of fungi are like those of other plants in the sense that the cell walls can be envisaged as a complex system of microfibrils in an amorphous matrix.

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