294 
Ishikawa.—Studies on the Embryo Sac 
synergid in its general appearance. This relation is clearly perceivable 
if Figs. 2, 3, v., PI. VII, are compared with those above mentioned. 
The fusing sex nuclei have been observed many times. They come in 
contact in the resting condition, simply fuse, and give rise to a larger 
nucleus containing two main nucleoli of different sizes, that derived from the 
male nucleus being smaller than that from the egg nucleus. I, 2, 3, 4, 
Text-fig. V, illustrate their behaviour at the critical moment of the fusion 
of both elements, and 5 and 6 show the same cases in the polar 
and sperm nucleus. Attention has been paid to the question of the 
plasma inclusion between two fusing nuclei, as stated by Brown ( 5 ) in 
Peperomia Sintensii or in Gagea lutea by Nemec ( 49 ), but in Oenothera 
no trace of such bearings was found. Sometimes 
the pole nucleus was found just receiving a dis¬ 
organizing male nucleus as shown in Text-fig. V, 7. 
This fact shows occasional disintegration of 
the male nucleus, and perhaps subsequent arrest 
of further growth of the polar or egg nucleus, if it 
happens to visit the latter. 
After the fertilization has taken place, the 
chromatic plasma coat which covers the egg-cell 
soon disappears, probably having been absorbed, 
and the lower end of the egg-cell also acquires a 
distinct cellulose membrane, which is clearly visible 
when the plasmolysis of the contents has oc¬ 
curred. Some starch grains are carried out from 
the synergid by the plasma flow, in which they are 
found spherical or ellipsoidal but not spindle- 
shaped. This fact shows that the grains are 
undergoing some chemical change. The fate of 
these starch grains has not been followed, but it 
may be presumed that they become finally con¬ 
sumed. The remaining corpuscles in the synergid generally retain their 
original form and seem to remain unchanged, until they become absorbed 
together with the shrunk synergid when the fertilized egg begins to 
develop. The division of the primary endosperm nucleus quickly follows 
the fertilization, resulting in the migration of two daughter nuclei to 
both sides of the egg apparatus (PI. VII, Fig. 10, end n.) when the 
division has succeeded twice. This nuclear position served as a clue 
to determine whether fertilization has taken place or not. As shown 
in Fig. 10 and Text-fig. V, 8, generally the divided nucleus still 
possesses two nucleoli ; such nuclear condition is retained through 
many nuclear generations (Text-fig. VI). The mitotic figures of the 
endosperm nuclei were often found in the preparations, but no favourable 
through plasma sheet with 
sixteen endosperm nuclei, 
showing two nucleoli in each 
of them, x 450. 
