I 
1918] BUCHHOLZ—PINUS 207 
material studied were poorly pollinated, as was indicated by the 
relatively few good ovules and seeds developed per cone, no doubt 
the maximum possible number of embryos was not to be found in 
these collections. 
The terminal embryo of the group is the successful one in the 
struggle for supremacy among the embryos. In very exceptional 
cases the successful embryo has been found to be the second one 
instead of the terminal. Occasionally an embryo develops with 
the reversed orientation, and the abortive embryos are frequently 
found in this reversed position. 
Cases were also found where less than 4 primary embryos were 
produced from an archegonium, where one of the vertical rows 
of cells was aborted with little or no elongation of its suspensor, 
or the embryo initial cell itself was aborted. This condition might 
give the impression that one of the 2 or 3 primary embryos is 
composed of 2 vertical rows of cells that failed to separate in the 
normal way, were it not for the fact that when one of the embryos 
aborts in this way there are less than 4 suspensor tubes or first 
embryonal tubes. 
No embryos have been found to arise from 2 or more vertical 
rows of cells combined. Such an embryo would have 2 apical 
cells, and wherever an embryo possesses a single apical cell and 
looks normal in other respects it is safe to conclude that it has come 
from one of the 4 embryonal cells. Another simple criterion is that 
of tracing the suspensor back to the rosette. If an embryo could be 
found attached to 2 primary suspensor cells, without the possi- 
bility that an embryo has been lost in dissection, it would indicate 
that 2 primary embryos were combined, but in this case the 
embryo should also have the appearance of being double, and the 
number of embryos present in the complex should be one less than 
the usual number. The writer found several cases which he sus- 
pected to be double embryos, but when they were more carefully 
studied they failed to fulfil these conditions. 
Twrys.—So far as I have been able to find, no embryos arise 
by a further splitting of one of the 4 primary embryos. Since the 
terminal cell of the early embryo is an apical cell, an equal splitting 
could only occur after the formation of a vertical wall, as in figs. 10, 
