Mas see. — A Monograph of the Geoglosseae. 233 
specially large organs, such as asci, cystidia, or hairs, have 
to be produced, a usual method of effecting this is by the 
amalgamation of the apical cells of two independent hyphae. 
The recent researches of Harper 1 on the sexual mode of 
reproduction in Sphaerotheca Castagnei tend to show that 
the observations of De Bary bearing on the question of 
sexuality in the Ascomycetes were in the main correct ; never- 
theless Harper’s more detailed account rather upsets the 
generally accepted idea that the Ascomycetes are derived 
from the Phy corny cetes, he having shown that in Sphaero- 
theca — the genus which more especially led De Bary to 
entertain this view — after fertilization of the carpogenic cell, 
a series of superposed cells is formed, and from one of these, 
and that not the terminal one, the ascus is formed ; hence 
the ascus in Sphaerotheca is not directly homologous with 
the oogonium of the Phycomycetes. 
It is the tendency at present to endeavour to trace groups 
presenting a general morphological resemblance to a common 
origin ; nevertheless, the large group of organisms described 
by Thaxter 2 under the name of Laboulbeniaceae are morpho- 
logically characteristic Ascomycetes ; yet the universal sexual 
mode of reproduction in this group by non-motile antheridia 
and trichogynes is essentially Floriaean in character, and 
difficult to reconcile with the sexual process as described by 
Harper in Sphaerotheca , also a typical Ascomycete, and seems 
to necessitate the admission that what we at present term 
Ascomycetes will prove to be a heterogeneous assemblage, 
and that the single bond of agreement — the production of 
ascospores — does not necessarily indicate a unity of origin 
of the members possessing this feature. 
1 Die Entwickelung des Peritheciums bei Sphaerotheca Castagnei, Ber. d. 
Deutsch. Bot. Gesellsch. Bd. XIII, Heft io, 475, 1895. 
Ueber das Verhalten der Kerne bei der Fruchtentwickelung einiger Ascomyceten, 
Prings. Jahrb. 1896, 655, Taf. XI-XII. 
2 Contribution towards a Monograph of the Laboulbeniaceae, Mem. Amer. 
Acad., XII, No. hi, 1896. 
