12 BROOKLYN BOTANIC GARDEN MEMOIRS 
gone would still represent the nearest approach of the phycomycete 
type to the ascomycete type. The method of conjugation of the 
gametangia, and the growth of the zygote, in Endogone sphagnophila, 
is surprisingly like that in Eremascus fertilis and in Dipodascus. Even 
without the knowledge of germination of the resting zygotes in Endo- 
gone, the genus seems to offer more of the characteristics of a prototype 
of the Protoascomycetes (and perhaps also of the Uredinales) than 
any other known phycomycete.’ Endogone presents additional strong 
evidence of the phycomycete ancestry of the Ascomycetes. 
All of the evidence considered, it appears to point more strongly 
to the zygomycete alliance as the source of the primitive ascomycete 
stock, rather than to the oomycete alliance. In the oomyeetes the 
sexual organs and the processes of fertilization have become very 
highly specialized. The sexual organs are highly differentiated; one 
or more distinct eggs are differentiated in the oogone, in many cases 
the protoplasm being differentiated into ooplasm and _ periplasm; 
while a special fertilization tube from the antherid penetrates the 
oogone, or in a rare and specialized case a motile sperm enters the 
oogone through a pore (Monoblepharis). 
In the zygomycetes the sexual organs have retained a simple and 
generalized condition. Copulation is by pore formation with merging 
of the content of the gametangia. In most cases the gametangia are 
equal and the zygotes mature im situ, within and comprising all of 
both gametangia. Progression in the zygomycetes, however, is mani- 
fested in five directions. 
1. Ina tendency to differentiation in size of the gametes. 
2. A tendency to differentiation of the gametangia in function, 
the larger one becoming the receiving gametange, the oogone, but 
without differentiation of content into egg and periplasm; the other 
serving as the supplying gametange, antherid (Conidiobolus utriculosus, 
Basidiobolus ranarum, Dispira americana Thaxter, 1895, Endogone 
lactiflua, etc.). 
3. The progressive tendency shown in the germination, or out- 
growth, of the young zygote immediately after fusion from the copu- 
lation point, or from one of the gametangia, the ripe zygote being formed 
outside the gametangia, not within them according to the typical 
process. The tendencies in this direction appear at different levels 
in the zygomycete alliance. Examples are Piptocephalis freseniana, 
6 The following forms among the phycomycetes have been suggested as proto- 
types of the ascomycetes. The Peronosporales by de Bary (1881) for the usual 
ascomycete type, Piptocephalis for the Eremascus type; Myzocytium and Protascus 
by Dangeard (1903-06, 1910), Cystopus by Lotsy (1907) and Monoblepharis by 
Nienburg (1914). 
