LABOULBENIALES 365 



Ceratomycetaceae. — This family of a few small genera on aquatic 

 insects contains some of the most striking forms, yet little studied 

 ontogenetically. 



In Ceratomyces mirabilis, the young individual consists of a simple 

 series of superposed cells, of which the distal begins to branch at an early 

 age. One of the intercalary cells of this series divides longitudinally, the 

 upper cell becoming a finger-like projection, the primordium of the peri- 

 thecium. The primordium divides into three cells, the upper becoming 

 the simple trichogyne, the middle the trichophoric cell and the basal, not 

 projecting from the axis of the plant, becoming the carpogenic cell. The 

 sister cell to the primordium divides into an outer and an axial cell. The 

 lower cell has also divided longitudinally into two cells, one of which 

 grows outward and upward, forming one row of the wall and canal cells of 

 the mature perithecium. The axial cell apparently gives rise to the other 

 three rows. These wall cells grow beyond and around the carpogenic and 

 trichophoric cells and, by subsequent division, form the perithecium. 

 The development of the perithecium will be described in greater detail in 

 the Laboulbeniaceae (p. 369). The spermatia develop from the segmen- 

 tation of slender branches into bacilliform bodies which fall from their 

 attachment as soon as formed. Rhynchophorotnyces rostratus {Cerato- 

 myces rostratus) has the same general ontogeny (Fig. 253, 1) except that 

 the whole base of the appendage becomes incorporated with the develop- 

 ing venter of the perithecium until it seems to arise from the wall cells. 

 The neck in this species becomes abruptly reflexed at maturity. 



In Coreomyces we have a new type of perithecial development. The 

 young individual of Coreomyces Corisae consists of three cells, from the 

 uppermost of which appendiculate cells are cut off distally. Above 

 the appendiculate cells is a series of four to six superposed cells terminated 

 by a sterile appendage. Thus there are three regions of which the two 

 basal cells form the receptacle, the appendiculate cells the antheridia, 

 while the distal region forms the perithecium. As the development 

 proceeds, the sub-basal cell of the distal region proliferates into the cell 

 above, while the sterile appendage above breaks off (Fig. 245, 3). The 

 penetrating branches, usually two corresponding to the posterior basal 

 cell and the secondary stalk cell of the ordinary perithecium (p. 370), con- 

 tinue to develop the perithecium. The developing perithecium destroys 

 the septa of the cells above, sending the trichogyne through the septum 

 at the base of the previous sterile appendage (Fig. 245, 4). At maturity, 

 the vestigial wall cells of the perithecium degenerate, leaving the develop- 

 ing ascogonium surrounded only by the walls of the original cells of the 

 distal region, a pseudoperithecium (Fig. 250, 2). Thus the asci and 

 spores finally float free within a structure resembling a perithecium and 

 performing the same function, but ontogenetically having little in 

 common with a perithecium. 



