Embryo of Cryptomeria Japonica. 425 
The result is that there are only three potential spores formed from the 
mother-cell. 
As stated above, there may be three or four megaspore mother-cells 
organized in Cryptomeria. As the early stages of the spindles of the first 
division were not found, I was unable to study the behaviour of the 
chromatin. Fig. 13 shows a spindle of the first division of one of the 
mother-cells with the daughter-nuclei already organized at the poles. 
The next stage observed showed a large group of spores as illustrated 
in Fig. 14. The contents of these megaspores were devoid of starch, and 
quite different in appearance from those of the mother-cells. They varied 
from twelve to sixteen in number, showing without much doubt that each 
mother-cell gives rise to four megaspores. As shown in Fig. 14, the one 
that is more centrally situated becomes larger than the others, and it 
probably is the only one that germinates. As this central megaspore 
increases in size, free nuclear division proceeds at a rapid rate. Meantime 
the other spores show all stages of disorganization, and are very probably 
absorbed by the young prothallium. These early stages in the develop- 
ment of the gametophyte progress slowly, for about a month after the 
organization of the megaspores we find the condition represented in 
Fig. 15. It will be observed from this figure that the greatest growth 
of the young prothallium has taken place in the direction of the chalaza. 
There are a number of vacuoles present, and the numerous free nuclei 
are distributed irregularly throughout the strands of cytoplasm. Up to 
this time the conditions are very much the same as those observed in 
Sequoia (Lawson, ’ 04 ). 
As the young prothallium increases in length, the vacuoles increase 
in size, and eventually flow together, forming one very large central 
vacuole as in Sequoia (Arnoldi, ’01 ; Lawson, ’ 04 ), Taxodium (Coker, ’ 03 ), 
Taxus and other Conifers. The result of this is that the cytoplasm is 
crowded to the wall, and appears in the form of a very thin parietal layer, 
in which the free nuclei lie imbedded at more or less regular intervals, as 
indicated in Fig. 16. A higher magnification of the parietal layer is shown 
in Fig. 19. It will be seen that the thickness of the cytoplasmic layer is 
just about equal to the diameter of the nuclei. 
The most striking difference between the young female gametophytes 
of Sequoia and Cryptomeria up to this stage is in the entire absence in the 
latter of any secondary prothallia. It will be remembered that in Sequoia 
one or two secondary prothallia, while failing to produce true prothallial 
tissue, nevertheless reach an advanced stage of development. In Cryptomeria 
only one of the megaspores germinates, and there is consequently but one 
primary prothallium formed. 
The next stage in the development of the prothallium showed a con- 
siderable increase in the thickness of the parietal layer of cytoplasm, and 
