556 THE AMERICAN NATURALIST. |. (Vor. XXXIX. 
genesis in the Saprolegniales. Trow (:04) believes that some 
of these forms are sexual but there can be little doubt that the 
group as a whole is generally apogamous. There is probably 
much apogamy in the Ascomycetes and an almost entire suppres- 
sion of sexual organs in the Basidiomycetes but no clear instance 
of parthenogenesis (č. e., a development from a cell whose mor- 
phology is unquestionably that of an egg) is known in either of 
these groups. 
Parthenogenesis is not known in the bryophytes and pterido- 
phytes excepting for Marsilia (Shaw, '97 ; Nathansohn, :00). 
Although there is much apogamy in the pteridophytes, especially 
in the leptosporangiate Filicales, the new generation generally 
develops as a bud-like outgrowth on the prothallus (vegetative 
apogamy). There have been no nuclear studies on the parthen- 
ogenetic Marsilia but an interesting preliminary account has 
'appeared announcing nuclear fusions in the apogamous develop- 
ment of Nephrodium (Farmer, Moore, and Digby, :03). 
Parthenogenesis is now known in the spermatophytes for 
Antennaria alpina (Juel, '98, : 00), several species of Alchemilla 
(Murbeck, :o1a, : orb, : 02 ; Strasburger, :04c), Thalictrum pur- 
purascens (Overton, :02, :04), Gnetum (Lotsy, :03), a number 
of forms of Taraxacum (Raunkiaer, :03; Murbeck, :04), sev- 
eral species of Hieracium (Ostenfeld, : 04a, : o4b ; Murbeck, : 04), 
Wikstremia indica (Winkler, :05), and is suspected for Ficus 
Treub, :02) and Bryonia dioica (Bitter, :04). A number of 
cases of polyembryony were formerly considered examples of 
apogamy but are now known to be developments from the nucel- 
lus and consequently vegetative buds of sporophytic origin and 
entirely independent of gametophytic activities. The best known 
of these forms are Funkia, Ccelebogyne, Citrus, Opuntia, and 
Alchemilla pastoralis. Vegetative apogamy is illustrated in the 
development of embryos from antipodal cells as in A//ium odorum 
(Tretjakow, '95 ; Hegelmaier, '97) or from the cells of the endo- 
sperm as in Belanophora (Treub, ’98 ; Lotsy, 99). Synergids 
have been reported to form embryos in a number of forms but 
many of these have proved to be cases in which the synergid is 
fertilized by a sperm nucleus and not examples of apogamy. 
However, synergids are known to develop embryos apogamously 
