SAX: FERTILIZATION IN FRITILLARIA PUDICA 509 
In most cases the pollen tube enters the embryo sac somewhat 
from the side after turning from the micropyle, but sometimes it 
penetrates the nucellus and embryo sac directly from the micro- 
pyle. 
The pollen tube just after entering the embryo sac is rounded 
and swollen at the tip. Only one case was found at this stage 
but it was well fixed, very clearly stained and apparently normal. 
The pollen tube and embryo sac are cut longitudinally. The 
pollen tube contains the two male nuclei. They stain darkly and 
are much elongated. Two other nuclei are also seen in the sec- 
tions of the tube. The male nucleus (a) nearest the tip shows in 
Fics. 3A and 3B. It is long and much coiled and consequently 
cut across at several places. The second male nucleus (0) is seen 
mostly in Fic. 3C, but the ends of the nucleus are seen in Fic. 3B. 
This male nucleus is not so long and coiled as the other. The 
second male nucleus and perhaps the first one are somewhat 
pointed at the end. The contents at this stage are in an irregular 
network which takes a deep red stain with saffranin., The 
chromatin is not entirely peripheral as is shown where the male 
nuclei are seen in section. To the right in Fic. 3C is a nucleus 
(d) of practically the same size, shape and appearance as the 
synergid nuclei. The nucleus of the synergid into which the 
pollen tube has passed, is not found elsewhere in the embryo sac. 
To the left in -Fic. 3C is a second vegetative nucleus (c) which is 
flattened and irregular in shape and situated between the two 
male nuclei. Portions of these vegetative nuclei are seen in Fic. 3B. 
Fic. 3A contains some dark-staining granules. The pollen tube 
did not stain nearly as darkly as others in the same ovary where 
the male nuclei had already escaped. It is questionable whether 
both of the vegetative nuclei, (¢) and (d), are tube nuclei, or whether 
the one to the right (d) is the synergid nucleus which has been 
surrounded by the pollen tube. 
The examples of stages in fertilization described so far are 
comparatively few. But after the male nuclei leave the pollen 
tube, numerous examples of the stages are found. Not less than 
eighty male nuclei were found free in the cytoplasm of the cells 
of the embryo sac, and typical cases of these are figured. 
On leaving the pollen tube the male nuclei apparently retain 
