446 Campbell . — The Gametophyte and Embryo of 
The Embryo. 
The genus Botrychium shows a remarkable diversity in the structure 
of the embryo and young sporophyte, and the writer has recently had 
occasion to call attention to this. While in B. obliquum and B. virginianum 
the cotyledon is remarkably well developed, in B. lunaria the cotyledon is 
reduced to an insignificant rudiment, and several more subterranean leaf 
rudiments are formed before the first foliage leaf appears above ground. 
B. obliquum differs from the other known species in the presence of 
a conspicuous suspensor, discovered by Lyon . 1 The embryo of B. simplex , 
as might be expected, more nearly resembles that of B. lunaria , to which 
Text-fig. 3. A. Fertilized archegoninm containing a unicellular embryo, x 300. b. Two- 
celled embryo. x 300. C. Two-celled embryo.showing oblique basal wall. x 300, D. Three longi- 
tudinal sections of a four-celled embryo showing no vertical divisions. X 300. E. Longitudinal 
section of three-celled embryo, x 300. 
it is undoubtedly pretty closely related, than it does either B. obliquum or 
B. virginianum. However, there are differences, especially the much 
better developed cotyledon, which distinguish it from B. lunaria. How con- 
stant these differences are must remain for the present somewhat uncertain. 
As in B. lunaria , the embryo may begin to develop while the game- 
tophyte is extremely small, and often several archegonia are fertilized at 
about the same time, and begin to develop the embryos. As a rule at 
least, only one embryo develops beyond the earliest stages, and reaches 
maturity. Unicellular and two-celled embryos were frequently encountered, 
but the later stages were very much less common. 
1 Lyon, H. C. : A New Genus of Ophioglossaceae. Bot. Gazette, xl, 1905. 
