228 



MONOGRAPH OF THE LABOULBENIACEiE. 



crushing perithecia in some aqueous stain like eosin, perfect asci in various stages of 

 maturity are very easily obtained, either free or still attached to the ascogenic cell. 

 Before they separate from their attachment, the asci are generally much distorted by 

 mutual pressure, but assume a more or less regular form after they have become free. 



As the ascus mass or masses increase in size, their upward pressure soon destroys 

 the superior supporting cell, as we have already seen ; while their downward pressure 

 in most instances destroys the primary and secondary inferior supporting cells, at the 

 same time freeing the ascogenic cells from one another, if there are more than one ; so 

 that the latter eventually lie in the cavity of the perithecium, free and unconnected with 

 any other cells. In some cases the inferior supporting cell persists after the ascogenic 

 cells have freed themselves from their attachments, as is the case to a certain extent in 

 Stigmatomyces, the supporting cell in this instance being so placed as to be protected by 

 the basal cells of the perithecium which surround it. In a similar manner the inferior 

 supporting cell in the species of Laboulbenia allied to L.pulmella persists permanently, 

 for the reason that it is surrounded by the lower series of wall-cells of the perithe- 

 cium, which are modified to form a perithecial stalk, and corticate it completely. 

 The further destructive action of the ascus masses on the parietal and canal cells of 

 the perithecium has already been described in connection with Stigmatomyces. 



With the formation of the spores and the disappearance of the ascus-wall, the his- 

 tory of the female organ and its products is completed ; but, as we have seen, the 

 changes which it has undergone are accompanied by changes in the cells of the peri- 

 thecium proper which are also subject to certain variations from the course ot 

 development described as characteristic of Stigmatomyces. 



In all cases the perithecium proper, by which is meant all portions of it exclusive 

 of the female organ and its products, originates as a single cell (Plate I, fig. 10, c; 

 Plate III, fig. 14, c) that lies wholly below the terminal cell which gives origin to the 

 female organ in the manner above described. This cell, which has already been 

 alluded to as the primordial cell of the perithecium, divides, in cases which have been 

 followed out and probably in most if not in all of the other genera / into two cells more 

 or less obliquely superposed (Plate I, fig. 11, c c", and Plate III, fig. 15, c',c"); tfie 

 divisions of which follow in general the same course which has been described in 

 Stigmatomyces, and may be briefly recapitulated with reference to the genus Enar- 

 thromyces. Comparing figs. 15-17 of Plate III, which represent three successive 

 stages of development, we have in fig. 15 the condition just referred to, in which 

 the primordial cell of the perithecium (fig. 14, c) has divided into two obliquely 

 superposed cells (c) and {c"). In fig. 1G each of these has divided, (c") into the stalk- 



