222 



MONOGRAPH OF THE LABOULBENIACE^E. 



sterile, while the others constitute the ascogenic cells, and at once begin to bud up- 

 ward ; the buds (fig. 21, as) developing into asci (fig. 12, as), and in this, as in a 

 majority of cases, arising in a more or less distinctly double row. (See Plate I, fig. 

 38 ; Plate III, fig. 1 ; Plate V, fig. 18.) 



In Stigmatomyces the four ascogenic cells, but two of which appear in the figures, 

 are at first symmetrical neither in form, size, nor arrangement ; but, as the asci 

 begin to develop, become so placed that one is anterior, one posterior, and one lateral 

 on either side. In fig. 23, which represents an antero-posterior view, the two 

 lateral ascogenic cells are shown, placed more or less symmetrically with reference 

 to one another, the anterior and posterior ascogenic cells (not shown in the optical 

 section) occupying a similar relative position in front of and behind them. 



Eeturning now to the perithecium proper, which we left in the condition repre- 

 sented in fig. 15, it will be remembered that it originated as a single cell (fig. 10, c), 

 which has divided several times, and that the upper products of these divisions have 

 grown up around the base of cell (d), from which, as we have seen, the female organ is 

 developed. In this stage (fig. 15), it will be seen to consist of the stalk-cell (p), the 

 secondary stalk-cell (Ji), and three basal cells (o), but two of which are visible in the 

 figure, and four primary wall-cells (n,n), which surround the carpogonium (/) and the 

 base of the trichophoric cell (e"). At a stage slightly earlier than that represented in 

 fig. 15 a further development from the three basal cells takes place, which is not indi- 

 cated in the optical section. This development consists in the upgrowth from the basal 

 cells (o) of four cells corresponding to the wall-cells, but alternating with them and 

 lying partly between them and the carpogonium. As they continue to grow upward 

 and to increase in size, they separate the wall-cells completely from the structures de- 

 veloped from the carpogenic cell, growing up around the latter in a fashion exactly 

 resembling that of the wall-cells. There are thus developed from the three basal 

 cells, eight cells arranged in two series; an outer, the primary wall-cells, four in num- 

 ber ; and an inner, also consisting of four cells. The further growth and the succes- 

 sive divisions of the cells of these two series, although its course is identical, is, 

 nevertheless, quite independent in either case ; the divisions of the cells of the inner 

 series occurring in general after those of the outer series have taken place. The 

 further development consists simply in a continued upward growth around the products 

 of the division of the female organ, accompanied by the separation of a terminal 

 portion. The latter is then again separated into two portions, the upper of which 

 divides again, and so on, until the number of cells characteristic of the genus or species 

 has been formed. This process may be made somewhat clearer by reference to figs. 



* 



