230 



MONOGRAPH OF THE LABOULBENIACEiE. 



cells ; but in some species they may lie wholly below them, being prolonged into a stalk, 

 as in L. lonyicollis, L. KunkeU, and their allies (Plate XIX, fig. G, etc.; Plate XVIII, fig. 

 9). In such instances the ascus and spore masses, as they lie in the perithecium, are 

 almost completely surrounded by the sub-basal cells of the series. In Stirjmatomyces 

 Baeri, on the other hand, the basal cells of the series occupy a corresponding position 

 (Plate I, fig. 23), while in S. virescens (Plate VIII, fig. 2) the basal cells of the perithe- 

 cium (not the wall-cells) extend up above the ascogenic cell and the base of the ascus 

 mass. In a few cases the wall-cells may give rise to projections or definite appen- 

 dages, which originate as lateral branches. Such a projection from one of the basal 

 wall-cells is found in ChUonomyccs spinigerus (Plate VIII, fig. 16). C. appcndiculaius 

 offers an example of a similar projection from one of the sub-basal cells; while in- 

 stances of outgrowths from the terminal cells of the series are sometimes found, as in 

 Stigmatomyces virescens (Plate VIII, fig. 1), Laboulbenia Gyrinidarum (Plate XXII, fig. 

 37), and a few other cases. In the genus Ceratomyces, multicellular appendages may 

 be thus developed which may be even copiously branched (Plates XXIV and XXV) ; 

 but in all the instances cited these structures are only of specific importance. 



The terminal cells of the series of wall-cells have been already referred to as the 

 "lip-cells"; since it is between them that the spores eventually force their way out 

 from the perithecium. These lip-cells are often somewhat modified in shape, and are 

 not, as a rule, similar and symmetrical, though sometimes so. They are usually 

 modified to form a more or less elastic margin to the pore ; as, for example, in some 

 species of Laboulbenia (Plate II, fig. 14), the lip-cells of which are in general very 

 irregular in form, and have their walls so modified as to give them great elasticity 

 and thus regulate the discharge of spores. In this genus, and perhaps in some others, 

 there is a peculiar structure at the apex of at least one of the lip-cells, represented in 

 the figure just cited at (x), which may perhaps act as a valve, allowing the lip-cell, 

 the cavity of which it terminates, to be more readily compressed, and at the same time 

 to recover its form as soon as the pressure is removed. That the spore discharge may 

 be regulated by modifications of cells other than the lip-cells has already been seen in 

 the case of Stigmatomyces (Plate I, fig. 24) ; and in Sphaleromyces (Plate III, fig. 1), 

 several sets of cells appear to assume this office. Rhadinomyces (Plate IX, fig. 13) 

 affords an instance in which the lip-cells perform this function without any consider- 

 able modification. 



Turning now for a moment to the inner series of cells which have been described 

 as arising from the basal cells of the perithecium within, and alternating with, the 

 wall-cells, we have seen that in Stigmatomyces their development follows that of 



