730 
DUNCAN S. JOHNSON 
become really female in character. It seems to the writer, espe- 
cially in view of the early distinction of the micro- and megaspo- 
rangium initials in Marsilia (Johnson '98), that the view of Stras- 
burger ('09, p. 12), is still tenable — that all the spore-mother- 
cells formed in the microsporangium are essentially male and 
those in the megasporangium are essentially female. 
Sehganella resembles Marsilia in that the gametophytes are 
unisexual and the sporophyte hermaphrodite, but it differs in 
that the sexes become distinct considerably earlier in the develop- 
ment of the sporophyte than in Marsilia. In fact, the sporo- 
phylls bear one kind of sporangium each. In erect spikes, those 
sporophylls at the base of the spike bear megasporangia only, 
those at the tip, microsporangia only. In the prostrate spikes 
of other species, megasporangia occur on the sporophylls turned 
toward the earth, while in species with drooping spikes the\ are 
found at the tip only (Hieronymus ('00), p. 659). 
In such conifers as Pinus and Larix, and in monoecious angio- 
sperms, the gametophytes are male and female, and the spor- 
ophyte is hermaphrodite, but the separation of the sexes is evi- 
dent at a still earlier stage than in Selaginella. Microsporangia 
and megasporangia are borne not merely on different sporophylls 
but even on different branches, that is, in male and female cones 
or flowers. 
In Cycas and Ginkgo and in dioecious angiosperm.s, the segre- 
gation of the sexes occurs at a still earlier stage, and male and 
female flowers are developed on entirely separated sporophytes, 
that is, the sporophyte, as well as the gametophyte, has becom.e 
apparently unisexual, like the zygosporic mycelium of Mucor 
mucedo. In these angiosperms the hermaphrodite condition exists, 
if at all, only in the fertilized egg, or, possibly, on into the early 
stages of the sporophyte. It is certainly evident that the sex of 
the sporophyte is fixed, once for all, at some stage of the sporo- 
phyte before that at which the first crop of flowers is borne. For, 
so far as the writer has been able to learn, perennial plants of this 
type bear flowers of the same sex year after year. 
In most angiosperms, while the gametophytes are unisexual, 
the sporophyte is hermaphrodite, so far as can be seen, up to the 
