1896. ] LEmbryo-sac of Alisma. 129 
preparation and staining were deficient. And subsequent de- 
velopments prove the wisdom of the caution. When we com- 
pare the size of an ordinary nucleus with a centrosphere it 
will be seen that the suggestion in the present case becomes 
one of great importance. 
No division of nuclei was observed in the pollen-tube. 
The two small nuclei in the tip of the tube, after it has en- 
tered the embryo-sac, are about the same size and take the 
Same stain as those in the pollen-grain. These are the two 
sperm nuclei which come from the generative nucleus. In 
this case the division of the generative nucleus occurs in the 
pollen-grain, while more commonly it does not take place 
until the tube is entering the embryo-sac, as shown by Guig- 
the power of fertilizing the oosphere, I could not determine. 
The appearance of the two nuclei after entering the embryo- 
Sac would indicate that only one was a true sperm nucleus. 
The fate of the vegetative nucleus was not discovered, but no 
trace of it was seen after the pollen-tube had entered the em- 
Ty0-sac, 
The early development of the embryo. 
It was not my intention to study the development of the 
embryo, but while making observations to determine the 
length of time that the nucleus of the remaining synergida per- 
“sted, I found that the development of the proembryo, as pre- 
ated in My sections, did not agree with the statements re- 
Sarding Alisma in the text books.!1_ After the union of the 
ae and female nuclei, the resulting nucleus divides in a di- 
ion 
(fig. 8) 
ucleus. This nucleus now divides again in the same 
nas the preceding division, making three nuclei for 
lo Se 
“ue Untersuch 3 
N Gc chungen, etc. 8. 
399. 19g Del's Outlines of Classification and Morphology, er rate 
7; and Sachs’ Text-Book of Botany, second Engl. edition, 5°9. : 
