232 



MONOGRAPH OF THE LABOULBENIACEiE. 



It should be mentioned in this connection that in two genera, (Dimorphomyces and 

 Dimeroinyces) not only do the parietal cells lose their individuality as cells, but also 

 the basal cells of the perithecium, the stalk-cell, and the secondary stalk-cell ; so that 

 the cavity of the stalk-cell and that of the body of the perithecium are continuous 

 when the latter is fully mature. In these cases, as in many other genera, the cavities 

 of the lower wall-cells of the perithecium are gradually obliterated, as the spore mass 

 increases ; the terminal and subterminal wall-cells often being the only ones, in old 

 individuals, in which the cell cavity can be made out. 



Before leaving the subject of the derivation of the two series of cells which consti- 

 tute the outer and inner portions of the body of the perithecium proper, and of their 

 relation to the cells below, it must be confessed that my first impression concerning 

 the origin of the inner series was that they arose from the primary wall-cells (Plate I, 

 fig. 15, n), through the formation of longitudinal tangential septa, it being a matter of 

 great difficulty to make out their exact position and relations at the earliest period of 

 their development ; and it was not till the protoplasmic connections of both the outer 

 and inner series was observed with some exactness, in specimens of Laboulbenia the 

 cells of which had been separated by treatment with potash, that the true condition 

 of things suggested itself. These connections, in so far as they have been absolutely 

 seen in given instances, are represented in figs. 16 to 18 of Plate II, which should 

 be compared carefully with the account above given of the successive origin of the 

 stalk-cell, the secondary stalk-cell, the basal cells, and the wall-cells ; the lettering 

 corresponding in general to that of the figures above cited on Plates I and III. In 

 figs. 16-17 (Plate II), the parietal cells, as well as the inferior supporting cell below 

 the ascogenic cells, had been destroyed, so that the protoplasmic connection with 

 these cells had also disappeared ; but in fig. 18, which represents a young individual, 

 some of them were distinctly visible, and it was apparent that the inferior supporting 

 cell (i s), and the two anterior basal cells (g) and (d), were definitely connected with 

 the secondary stalk-cell (h), and that the two visible parietal cells (pc) were similarly 

 connected with the two anterior basal cells. A second preparation showed with equal 

 distinctness that the posterior basal cell (d) was similarly connected with one of the 

 parietal cells. It was, however, impossible to determine which of the two anterior 

 basal cells gave rise to two and which to one parietal cell ; yet it is safe to assume that 

 the same cell (d) which (fig. IT) gives origin to two wall-cells, is also connected with two 

 parietal cells. In the preparation, as will be seen (fig. 18), three connections were vis- 

 ible from this cell : one of which was evidently with a parietal cell, another with the 

 wall-cell (/ ), the third running beneath and connecting on the opposite side either with 



