CARPOSPOREM. 



313 



slender branches now shoot out at opposite points, and grow upwards on the outside 

 of the helix ; one of these developes more quickly, reaches the uppermost coil, and 

 becomes closely attached to it by its apex (B, p). This branch is the poUinodium. 

 Conjugation takes place between its apex and that of the carpogonium, the cell-walls 

 being absorbed at the point of contact, and the protoplasmic contents of the two cells 

 commingle. Soon afterwards new filaments sprout out from the lower part of the 

 poUinodium and of the carpogonium, which increase in number, cling closely to the spiral 

 (C), and finally entirely envelope it. From these filaments a layer of polygonal cells (D) 

 is formed by numerous transverse divisions, which envelopes the carpogonium. The 

 cells of the enveloping layer grow inwards as papillae which become septate {E). While 

 the enveloping layer is increasing in size, the cavity of the perithecium, which is thus 

 enlarged, is filled up by the papillae, and they finally insert themselves between the coils 



Fig. 208.— Development oi Eurotiuvi repens (after De Bary). A small portion of a mycelium, with the conidia-bearing 

 hyphae c and young' ascogonium (or carpogonium) as; B the spiral ascogonium as with the poUinodium /; C the same, 

 beginning to be surrounded by the threads out of which the wall of the perithecium is formed ; D a perithecium ; E, F 

 section of young perithecia, w parietal cells, y pseudo-parenchyma, as ascogonium ; G an ascus ; H an ascospore. 



of the carpogonium which have now become looser. These papillae become divided 

 by septa into numerous cells of similar diameter, so that at last the space between 

 the enveloping layer and the coils of the carpogonium is filled by a pseudo-parenchyma 

 {F). During these processes a large number of septa arise in the carpogonium, and 

 soon there shoot from its cells numerous commencements of branches, which penetrate 

 on all sides between the cells of the pseudo-parenchyma, become septate, and ramify. 

 Their last ramifications are the asci (G), which therefore owe their origin to the 

 fertilised carpogonium. These internal changes are accompanied by a considerable 

 increase in size of the whole perithecium. During the development of the asci 

 the pseudo-parenchyma becomes looser, its cells round themselves off, become capable 

 of swelling, lose their fatty contents, and finally disappear ; in the ripe perithecium 



