1914] FARRELL—CYRTANTHUS SANGUINEUS 433 
which still envelops the growing point, and a long upper projection 
which has resulted from the greater growth in length of one side 
of the sheath. The tip of the shorter, aborted side of the sheath 
is seen at a in figs. 4, 5, and 15. The vacant space in this older 
embryo, unlike that of the younger, which was four-lobed, is now 
reduced to the narrow slit represented by s in figs. 13 and 14. 
The vascular conditions are indicated in fig. 5. In the lower region 
of the sheath (the completely enveloping region below the abortion) 
each side has two vascular strands, making four in all (figs. 8-13), 
which arise independently from the cotyledonary node and enter 
the two differentiated sides of the sheath, just as happens in many 
dicotyledonous seedlings (figs. 5 and 7). Near the tip of the lower 
or aborted side of the sheath, the vascular strands from that side 
abruptly enter the region of the extended side, and fuse with the 
vascular strands of that organ. 
At this stage of development, the growing point has differ- 
entiated the first and second leaves, the first arising on the side 
corresponding to the aborted side of the sheath, and the second one 
about opposite the first. All are closely pressed upon by the grow- 
ing sides of the sheath. These arrangements are shown in figs. 5 
and 10. The root cylinder is tetrarch (fig. 6). 
Discussion 
As was remarked before, the amount of endosperm in the seeds 
of Cyrtanthus is very great in proportion to the size of the embryo. 
This makes it difficult for the embryo to develop its organs to their 
full extent. I have noted how the originally large space within the 
sides of the sheath is reduced, little by little, as growth progresses, 
to a very small space (s, figs. 3, 13, and 14). Following out this 
process in thought, it is not difficult to imagine how the early 
condition indicated in fig. 3 might easily be changed into that of 
figs. 4 and 5 merely by the mechanical pressure of the large endo- 
sperm. In other words, the sheath of monocotyledons is probably 
a fusion of two or more cotyledons; the probability amounting 
almost to a certainty when we remember that the very same con- 
dition here described in a monocotyledon has been discovered in 
the dicotyledonous embryo of Microcycas, a complete fusion of the 
