SPHAERIALES 



273 



Meanwhile an antheridium arises on or near the ascogonial mass, 

 from the branch of a hypha which is not differentiated from the usual 

 vegetative hyphae. Later, its tip thickens, the terminal cell completes 

 many nuclear divisions and forms several (usually about three) lobate 

 projections (Fig. 180, 6) into which the nuclei migrate (mostly in pairs, 

 seldom 4 to 8). 



The trichogyne grows actively toward the antheridium. Thus in 

 Fig. 180, 6, at the exit of the perithecium, it changes its direction of growth 



Fig. 182. — Venturia inaequalis. Section through perithecium with young ascogenous 

 hyphae and paraphyses. The three large cells are empty ascogonial cells from which the 

 ascogenous hyphae grow. ( X 875; after Killian, 1917.) 



and, bending at a sharp angle, grows toward the antheridium at the left. 

 These cell processes surround the trichogyne, like the fingers of a hand. 

 By contact, the antheridium is stimulated to further development. Its 

 cells and nuclei multiply and enlarge and the recently formed sprouts 

 again clasp the lower portions of the trichogyne, so that the coils cover it 

 (Fig. 180, 7). 



When both organs are firmly united, a pore forms and the male nuclei 

 enter the trichogyne. Probably not only the nuclei in the copulating 

 antheridial branch enter, but also the others, since at the end of migration 

 all the antheridial branches seem empty. The male nuclei migrate to 

 the lower portion of the trichogyne (Fig. 180, 8). Neither of the tricho- 



