The Cytology of the Laboulbeniales. 
BY 
J. H. FAULL, 
University of Toronto. 
Introductory. 
A PRELIM IN ARY note on the cytology of the asciis of the Laboul- 
beniaceae was published by the writer in 1906. Since then a con¬ 
siderable quantity of material has been accumulated and the earlier studies 
on this exceedingly interesting group have been extended to many addi¬ 
tional forms and to the cytological phenomena of their entire life cycle. In 
the course of these studies the observations first recorded have been 
repeatedly verified, and many new facts have come to light. Several 
features are still under investigation. This introductory account of the 
researches so far accomplished will be followed by others dealing in greater 
detail with the topics presented below. 
I wish here to express my obligations to Professor Roland Thaxter for 
his generous interest and kindnesses throughout, and to Professors Farlow 
and Thaxter for the facilities of the laboratories of Cryptogamic Botany of 
Harvard University so kindly placed at my disposal during several months 
of last year. 
Spores. 
The spores are uninucleate in their earliest stages. The nucleus divides 
once before the spore is mature, but a septum immediately effects the 
separation of the spore contents into two cells. In Amorphomyces alone of 
all the genera examined does this septum not form, in which case the lower 
of the two daughter nuclei (with reference to the orientation of the spores in 
the ascus) at once degenerates, so that when the spores are shed they are 
non-septate and contain but a single nucleus. 
Tpiallus. 
The cells of the thallus are characteristically monoenergid. After the 
thallus has completed its normal growth, the nucleus in the larger cells of 
the receptacle of certain genera may undergo one or several divisions. This 
| Annals of Botany, Vol. XXV. No. XCIX. July, 1911.] 
