292 SUMMARY OF CURRENT RESEARCHES RELATING TO 



act of sexual conjugation. The staining material used was various 

 preparations of hgematoxylin. 



. In Pythium (with which Gystopm appears to agree) the nuclei 

 occur in considerable numbers in the mycelium, each having a very 

 large nucleolus. In young oogonia, before the formation of the 

 oospheres, the number is usually from ten to twenty. When the 

 oosphere is being formed, they collect together and coalesce into a 

 single large ovum-nucleus. In the antheridial cell only a single 

 nucleus was found, but this was probably the product of the coalescence 

 of several. This nucleus passes, with the gonoplasm, into the oosphere, 

 and coalesces with the ovum-nucleus. 



Among UstilaginesB, Tilletia, Urocystis, Ustilago, and Protomyces 

 were examined. The spores of these appear to contain only a single 

 nucleus, while the mycelial cells usually contain several, as also those 

 of the promycelium, and usually those of the sporidia. In the " copula- 

 tion " of the sporidia and mycelial cells, no coalescence of nuclei was 

 ever observed. In the mycelium which is formed subsequently to 

 " copulation," a number of nuclei generally enter with the protoplasm, 

 and are separated from one another by protoplasm, so that here therei 

 can also be no coalescence. In the Hymenomycetes also nothing of 

 the kind was observed. 



The general conclusion of tbe author is that in Pythium and its 

 allies there is a true process of sexual union ; but not in the Usti- 

 lagineas and Hymenomycetes. 



Classification of the Discomycetes.* — M. E. Boudier insists on the 

 importance of the mode of dehiscence of the ascus in the classification 

 of this family. In the fleehy Discomycetes there are only two modes 

 of dehiscence of the ascus — by a kind of apical operculum, and by a 

 foramen or perforation of the cell-wall at the apex. These two 

 groups, the Operculata and Inoperculata, are well defined, and the 

 tribes and genera may be further distinguished by characters drawn 

 from the receptacle, the form of the ascus, the paraphyses, and the 

 spores. The terrestrial Discomycetes, of a soft or waxy consistence, 

 belong to the Operculata ; whilst the epixylous or epiphytal species, 

 of more elastic consistence, which approach the Pyrenomycetes, come 

 under the Inoperculata. The whole group may be divided into six 

 tribes, as follows : — 



I. Opeeculata. 



1. Mitrese : — Morchelleee and Helvellege. 



2. Cupulese : — Ehizinese and Pezizese. 



3. Lenticulese : — Ciliariea&, HumariesB, and Ascoboles©. 



II. Inopbeculata. 



4. Clavulese: — Geoglossese and Leotieae. 



5. Carnoseee : — Ombrophileas and Callorieaj. 



6. Gatlmleae : — Helotiese, Dasyscypheae, and Urceoleae. 



* Bull. Soc. Mycol., 1885. See Bull. Soc. Bot. France, xxxii. (1885). Eev. 

 Bibl., p. 129. 



