FEE TILTS A TION 5 7 



meantime the contents of the cell, or oocyst, are being differen- 

 tiated into an inner wall and the contained ascus. The peri- 

 thecium gradually acquires its brown tint, with the formation 

 of sporidia in the ascus and the rooting filaments at its base, 

 and is then complete. In other species of Erysiphe oocysts 

 and antheridia are produced in a similar manner. 



The formation of perithecia in Eurotium is analogous (Fig. 

 34). The generative filaments twist together at their summit like 

 a corkscrew, generally presenting six turns closely united to each 

 other and forming a hollow body. Then follow the production 

 of a multitude of cells in the central cavity. De Bary thinks 

 it not impossible that at this time some act of fertilisation 

 takes place, but there is not even as much evidence in favour 

 as is adduced in the case of Erysiphe, and hence it remains as 

 a guess. 



The opinion of De Bary may have some weight, but it is in- 

 sufficient without the evidence, which thirty years following has 

 not produced, in support of this conclusion — that "the pheno- 

 mena which take place in Erysiphe authorise us to presume 

 that in others of the Ascomycetes, having isolated perithecia, 

 the stroma which encloses several conceptacles, or even the 

 organs of fructification in the Discomycetes, the Tuberaceae, and 

 other groups, are also the products of a sexual generation." 

 There is an abundance of instances in which pyrenomycetous 

 Fungi have two, three, or four distinct kinds of fructification, 

 but from this fact alone nothing can be concluded as to the 

 process of fertilisation or the existence of sexuality. 



In the Discomycetes, with its four thousand species, the 

 suggested examples of sexuality are but very few, and these 

 have not been confirmed. Woronin examined Zachnea pul- 

 cherrima, and succeeded, as he thought, in recognising that 

 the receptacle derives its origin from a short and flexible tube, 

 thicker than the other branches of the mycelium, which is 

 soon divided by transverse partitions into a series of cells, 

 since denominated a " scolecite." He seems also to have 

 assured himself that there is always in proximity to this body 

 certain filaments, the curved branches of which, like so many 

 antheridia, support their extremities on the " scolecite." This 

 contact would appear to communicate to the scolecite a special 



