MONOGRAPH OF THE LABOULBENI ACEJE. 



265 



septum, and from it arises a second projection, the upper portion of which is cut off as before, 

 and develops into a primary appendage, external to each primary perithecium. This condition 

 is represented in figs. 2 and 3. The same process may continue through the production of 

 further successive lateral proliferations, new cells being separated as above described, and develop- 

 ing upward into new perithecia and sterile appendages. As a result of this process a fan-like 

 habit is developed, a series of alternating perithecia and appendages extending obliquely upwards 

 on either side from their common point of origin in the median line of the receptacle, their 

 bases resting upon a unicellular margin (figs. 1 and 5), which results from its repeated pro- 

 liferation. The alternation of perithecia with appendages appears to be invariable ; except in 

 abnormal cases, where, for example, a perithecium has failed to develop, as at the left in fig. 1. 



The appendages themselves present no special peculiarities, and consist merely of a single 

 series of superposed nearly cylindrical cells. The perithecium originates from a single cell that 

 divides into a lower and upper portion, the former the primordial cell of the perithecium proper, 

 the latter of the procarpe. The development of the former is made out with great difficulty, 

 the septa being very indistinct. It is probable, however, that it corresponds in general with the 

 course of development described as typical in the first part of this memoir; although in the 

 mature perithecium all signs of septa have disappeared, and the cavity of the stalk-cell and of 

 the perithecium are continuous (fig. 3), the single ascogenic cell with its ascus mass floating 

 free within. 



The spores are of the usual type, and are once-septate. As in the genus Amorphomyces, the 

 members of any given spore pair produce one a male, the other a female individual ; the two 

 sexes being thus invariably associated, as in figs. 2 and 5. 



The male individuals are very similar in the two known species, and are often indis- 

 tinguishable. Owing to their minute size, I have been unable to obtain material of the youngest 

 stages for figuring, the only early condition observed having been unfortunately lost in an 

 attempt to mount it. In this specimen it was evident, as could be inferred from an examination 

 of the mature individual, that the antheridium was developed as a lateral production from the 

 sub-basal cell of the receptacle. The receptacle, as in the female, consists of four superposed 

 cells, the two terminal ones sterile. The antheridium itself consists of a basal cell, above which 

 are three small cells, of somewhat unequal size, from which the antheridial cells arise. The 

 latter are arranged in three pairs ; and all six cells discharge the antherozoids formed 

 within them into a common cavity, that forms the slightly inflated base of the long tubular 

 neck through which they are finally discharged. The formation and discharge of antherozoids 

 continues for a considerable period, so that provision is made for the fertilization of as many 

 secondary perithecia as may be formed upon the female individual ; and the number of antbero- 

 zoids eventually produced by a single individual must be very great. 



The genus appears to bear no special relation to Amorphomyces, which, in all essential points 

 of structure, with the exception of the I'emarkable similarity of its trichogyne, is widely different 

 in both sexes. Yet it is singular that these, which are, with one exception, the only two 

 dioecious genera so far discovered, should inhabit the same minute host. 



Scientifically considered, the three dioecious genera, of which this may be taken as a type, 

 may certainly claim a position first in importance among the Laboulbeniaceae, if not among the 

 Ascomycetes as a whole, since their morphology and development would seem to settle beyond 



