The Cytology of Laboulbenia chaetophora and 
L. Gyrinidarum. 
BY 
J. H. FAULL, B.A., Ph.D., 
University of Toronto . 
With Plates XXXVII-XL. 
T HE Laboulbeniales possess many fundamentally important morpho- 
logical features that cannot be properly interpreted until their under- 
lying cytological phenomena have been elucidated. This is especially true 
of their organs of reproduction, including both gametangia and spore-sacs. 
Thus the latter have been rightly denominated asci by some botanists, but 
in the absenceof any knowledge of their cytology — which recent investigations 
have shown to be essential to a definition of the ascus — others have advanced 
different views with regard to their nature, and correspondingly different 
speculations as to the taxonomic position of the group. By way of illustra- 
tion it is needless to go farther afield than Engler’s ‘ Syllabus ’ (’07), in which 
they are classified as Laboulbeniomycetes, a class of equal rank with the 
Ascomycetes and the Basidiomycetes. The gametangia have played an 
even more prominent part in these speculations. This is particularly true 
of the female organ, whose striking resemblance to that of the red seaweeds 
has won for it the name of ‘ procarp and given rise to the theory that the 
Ascomycetes are an offshoot of the Florideae with the Laboulbeniales as 
the connecting link. But every biologist nowadays realizes the unreliability 
of schemes of phylogeny, the sole capital of which is external morphology. 
The true homologies of the gametangia are quite as likely to be expressed 
by their cellular and nuclear phenomena. Hence, a knowledge of the latter 
is almost certainly needed before a satisfactory estimate can be made of 
any phylogenetic hypothesis based on the morphology of the organs of re- 
production. 
The sexual organs have also been of interest from another standpoint. 
Because they are well marked and apparently functional they have been 
cited as proof that the Ascomycetes have not parted with their sexuality. 
As a matter of fact, it has never been shown whether they are or are not 
sexually functional, or just how they may function — that remains to be 
determined by following patiently the fate of their nuclei. It is likewise 
[Annals of Botany, Vol. XXVI. No. CII. April, 1912.] 
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