260 BOTANICAL GAZETTE [APRIL 
selection may play a definite réle under normal circumstances. 
In /soetes there are usually several archegonia, so that it is possible 
for several eggs to be fertilized, at least occasionally, but nothing 
has been recorded concerning an actual plurality of embryos. 
Fic. 14 Fic. 18 
Fics. 14, 15.—Embryos of Selaginella apus showing polyembryony; fig. 15, 
fertilization of egg in archegonium beside another zygote; fig. 14 may represent two 
zygotes of neighboring archegonia such as those in fig. 15 (drawn to same scale) after 
gametophytic tissue between them was digested away; after Lyon (31). 
EQUISETALES.—HOFMEISTER (22) definitely states that in 
Equisetum arvense the number of archegonia of a vigorous prothal- 
lium is from twenty to thirty. It exceeds, therefore, the number 
of antheridia of the largest male gametophytes. As a rule more 
than one egg is fertilized. He 
counted as many as seven 
embryos on one such gameto- 
phyte. Fig. 16 shows E. ar- 
vense with two neighboring 
archegonia containing em- 
bryos in competition. In a 
whe Pe more recent study by KASHYAP 
efsofe LSTEAG j (26) on E. debile, the author 
Fic. 16.—Polyembryony in Eguisetum es ee 
arvense; after HorMEISTER (22). gametophytes the number of 
archegonia may reach two 
hundred or more. Although the prothallus may bear only a 
single sporophyte, eight to ten young sporophytes on a single 
gametophyte are said to be very common. Under conditions 
of laboratory culture KAsuyap obtained fifteen or more sporo- 
