BIOLOGY, MORPHOLOGY, AND CYTOPLASMIC STRUCTURE 
OF ALEURODISCUS 
Harvey E. Stork 
Biology of Aleurodiscus amorphus 
The results here reported are the outcome of observation and succeeding 
laboratory study of Aleurodiscus amorphus (Pers.) Rabenhorst as found on 
the balsam fir in the Adirondack Mountains, vicinity of Seventh Lake, 
Hamilton County, N. Y. This plant has been described under a number 
of different names, a fact due, in part, to its pezizoid form. Persoon first 
described it as Peziza amorpha. Fries made it a Thelephora and later a 
Corticium. Quelet put it into the genus Cyphella, and more recently 
Peck described plants from the Adirondack region as the type of a new 
genus Nodularia. The plant has characteristic moniliform paraphyses 
that give a suggestion of an ascus with large spores when examined under 
low magnification, and this has been one of the misleading characters. In 
dried plants, too, the contents of the basidia often round up into globular 
masses which have been mistaken for ascospores. 
This Aleurodiscus bears the distinction of being the first Basidiomycete 
in which a nucleus was definitely described, De Bary (7) having reported 
and figured in 1866 the fusion nucleus in the basidium. It is not surprising 
that this should have come to his attention, for the mature basidia are very 
large, reaching the size of 150 X 24^1; and the fusion nucleus (reaching 
15 is the largest that the writer has seen in the fungi or of which he finds 
report in the literature, if the peculiar nucleus of the chytrids be excepted. 
It was for this reason that the late Professor G. F. Atkinson suggested this 
plant to the writer in 191 5 as a good object for cytological study. Because 
of the large size of the nuclei, especially in the large basidia, it has been 
found a most favorable object for the study of nuclear fusion and of the 
behavior of the elements of the nucleus in karyokinesis. The study of this 
phase of the subject is, however, incomplete in some of the stages, and a 
discussion of the details of karyokinesis is left for a subsequent paper, the 
cytological part of the present study being limited to cytoplasmic structures. 
Another species of Aleurodiscus that resembles in many respects the 
one here discussed is A. Oakesii, commonly found on the bark of living 
Ostrya and less frequently on the bark of several other frondose trees. 
This species is also being studied by way of comparison with A . amorphus. 
Their fruit bodies are somewhat similar, but they are never found on the 
same hosts. The fruit bodies of A. Oakesii (upper and middle figures, 
Plate XXXI) are normally more or less cup-shaped, while those of A. 
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