MONOGRAPH OF THE LABOULBENIACE^. 



233 



a wall-cell or with a parietal cell. The fourth connection could not be distinctly made 

 out, and may well have been broken by the crushing which was resorted to in order to 

 separate the cells from one another. The connections of the basal cells with the wall- 

 cells, as they are represented in figs. 16 and 17, are very readily demonstrated. It 

 will be noticed that in fig. 17 a portion of the posterior basal cell (o'), as well as its 

 connection with the wall-cell (7), is indicated through the anterior basal cell (d), the 

 connections of which with two wall-cells (c) and (/) are very distinct. The connection 

 of the basal cell (g), shown in fig. 16, is not visible in this instance. 



Having considered these special cases and their modifications as far as they are at 

 present known, it may not be superfluous, even at the risk of tedious repetition, briefly 

 to summarize the general development of the perithecium and of the structures which 

 it contains, since it involves matters of such considerable importance that a clear 

 understanding of it is essential. 



Summary of the development of the perithecium and of the female sexual organs. The 

 perithecium arises as a lateral, rarely as a terminal organ, and consists at an early 

 stage of two superposed cells : an upper, which is alone concerned in the formation of 

 the female organ, and a lower, from which is developed the perithecium proper. The 

 upper cell elongates, by terminal growth, and is converted into the procarpe through 

 the formation primarily of two cross partitions, by which it is separated into a lower 

 portion, the carpogenic cell, always a single cell ; a middle portion, the trichophoric 

 cell, also always a single cell, and a terminal portion, the trichogyne, which may con- 

 sist of a single cell, or, through the formation of cross partitions often accompanied 

 by copious branching, of very numerous cells. The free extremities only, of the tri- 

 chogyne, are receptive, and conjugate with the antherozoids which adhere to them. 

 As a result of this union, the trichogyne soon withers and disappears, while the carpo- 

 genic cell undergoes a series of divisions. First, by the formation of two transverse 

 septa, it is separated into three superposed cells : the upper and lower constituting 

 the superior and inferior supporting cells, respectively, which undergo no further 

 changes ; while the middle cell of the three, known as the ascogonium, divides, by 

 more or less oblique partitions, into from two to nine cells, one of which lies at the 

 base of the others and is called the secondary inferior supporting cell; while the one, 

 two, four, or eight remaining cells are known as the ascogenic cells. Each ascogenic 

 cell then begins at once to produce asci, which bud from it downward outward and 

 upward, and soon becomes quite free in the cavity of the perithecium ; destroying, as 

 a rule, both supporting cells, and eventually the remains of the trichophoric cell, as well 

 as the cells of the perithecium proper (parietal and canal cells) which lie immediately 

 about and above it. 



