and Fertilization in Oenothera . 
291 
some more examples of the same stage as the latter. Fig. 13 illustrates 
a similar case, showing two male cells (m.n.) and egg nucleus (, e.n .) in 
the oosphere, the lower end of which has been cut off obliquely. 
It appears that two sperm cells always pass through the synergid before 
they reach either the egg-cell or the pole nucleus, although no direct proof 
Text-fig. IV. Twin embryo sacs of Oenothera nutans fertilized by Oe. pycnocarpa, both of which 
are attacked by pollen-tubes (p.) ; the right-hand one has already been penetrated by the tube and 
plasma flow ( p.f '.) from the synergid {syn. x ) is spreading over the oosphere ; on the lower end of the 
latter two sperm nuclei {m.n.) lie surrounded by a distinct plasma sheaf {p.s.), through which egg 
nucleus ( e.n .) is visible, syn., sound synergid; fit filiform apparatus; e.c., egg-cell; s.n., synergid 
nucleus ; p.n ., pole nucleus, x 1,300. 
has been obtained. When perched upon the egg-cell, two sperm nuclei 
are clearly seen, for each of them is covered with a hyaline plasma sheath, 
which is stained well with light green, while the poured plasma mass is very 
chromatic and is stained dark red with safranin. PI. VII, P'igs. 13 and 14, 
and Text-fig. IV were drawn from the preparations stained with a combina- 
U 'X 
