349 
Laboulbenia chaetophora and L. Gyrinidavum. 
mycetes, they occur most abundantly in terminal cells, from which any 
number of asci may spring, or from other cells which may or may not be 
definitely located. 
In view of these data I am thoroughly convinced that any investigations 
on the sexuality of the Ascomycetes and any phylogenetic scheme drawn up 
for the group must take cognizance of the phenomenon of conjugate nuclei 
or synkarions. It is admittedly manifest in the peripheral cells of the asco- 
genous hyphae throughout the class, except in a few forms that are marked 
by great simplicity. Indeed, it ranks here next in the regularity of its 
occurrence to the intricate phenomena in the ascus itself, and there is 
increasing evidence that the nuclear divisions in the ascogenous hyphae are 
of this type. Once having arisen, it is readily understandable how such 
a variation so favourable to increased sporogenous productivity from a single 
pair of gametes would persist and develop in one or several directions. The 
main difficulty arises in discovering just where the beginning was made. At 
some stage in the evolution of the group the principle must have been 
adopted. That is self-evident, for, regardless of differences of opinion as to 
its use, every one admits that this principle is utilized by all so-called typical 
sac-fungi. But where are these ancestors to be sought ? 
Many have held that the Laboulbeniales are the living representatives 
of the first sac-fungi and that they had their beginnings in the red seaweeds. 
But this phenomenon of conjugate divisions only adds another specializa- 
tion to the several of which no hint is given by the Florideae, and we know 
of no connecting links. It is true that our phylogenetic conceptions of the 
Ascomycetes are in such a plastic state that it is not inconceivable that 
delay in the fusion of gamete nuclei might have originated in some family 
of the Florideae, especially as there are good reasons for believing that this 
phenomenon has originated independently more than once in the Thallophyta 
But in the present state of our knowledge it would seem a more reasonable 
working hypothesis from many standpoints to look to the less specialized 
sac-fungi for the progenitors of the group. In them the gametes copulate 
and at once produce a single ascus. In Eremascus, for example, there is 
a fusion of the gamete nuclei followed by the immediate formation of an 
eight-spored ascus (Stoppel, (’07)). By a division of these nuclei before 
fusion two asci would have been possible, and by repeated divisions, several ; 
and by the elaboration of a system of synkarion carriers or ascogenous 
hyphae, an unlimited number. 
It is, of course, to be borne in mind that, starting with the primitive 
forms, whatever they may have been, in which the phenomenon originated, 
several parallel lines have probably been worked out in which advantage of 
this method of multiplying the reproductive powers has been retained and 
elaborated. At the same time there would have been other changes of 
importance, such, for example, as an evolution of the sexual organs in more 
