234 



MONOGRAFII OF THE LABOULBENIACEiE. 



The cells which make up the body of the perithecium proper, all arise, on the other 

 hand, from the primordial cell of the perithecium, which lies wholly below that of the 

 procarpe. Its first division, with a few possible exceptions, separates it into two more 

 or less obliquely superposed cells. From each of these cells upgrowths arise ; one 

 from the lower and two from the upper, which still retains its protoplasmic connection 

 with the primordial cell of the procarpe. The lower becomes separated from its single 

 upgrowth, and constitutes the primary stalk-cell ; while the upper is similarly separated 

 from its two upgrowths and constitutes the secondary stalk-cell. There are thus two 

 stalk-cells surmounted by three upgrowths which have become separated from them 

 and form three distinct cells, that begin to grow up around the base of the primor- 

 dial cell of the procarpe. The body of each of these cells constitutes one of the three 

 basal cells of the perithecium. From these three cells then arise eight upgrowths, 

 four of which are external, while the remaining four are included by them and form 

 an inner series. As a result of continued terminal growth, accompanied by the forma- 

 tion of a variable number of septa by which the growing tip is successively separated 

 from the portion below, an envelope is formed which completely encloses the female 

 organ and its products : consisting of an outer series of cells arranged in four rows, 

 each made up of a definite number of superposed cells, which constitute the wall-cells 

 of the perithecium ; and of an dinner series of cells similarly arranged, the lowest mem- 

 bers of which have been called the parietal cells, while those above them are termed 

 the canal-cells. Of the two series, the outer forms the perithecial Avail, the inner 

 being destroyed, with unimportant exceptions, to make room for the ascus and spore 

 masses, and to provide a channel through which the spores may pass to their point 

 of exit between the apposed terminal, or lip-cells, of the outer series. 



General Relations and Character of the Cells. We have already seen that the gelati- 

 nous membrane which surrounds the ripe spore persists, in the growing and in the 

 mature plant, as a general envelope within which the cells undergo their independent 

 divisions and modifications. This envelope, though thin, is tough and very impervious, 

 resisting the action of reagents and staining fluids in a manner which greatly increases 

 the difficulties associated with any attempt to observe the nuclear and other changes 

 that take place in the cells within it. In some cases it may be separated without 

 much difficulty, by treatment with potash, or even, when the specimen is dry, by 

 the application of water; the action in either case resulting in the swelling of the 

 outer layers of the cell walls and the bursting of the envelope, through which the cells 

 themselves may protrude while still connected, as is represented in Plate III, figs. 10 

 and 11. In other cases the envelope appears to be more firmly and intimately con- 



