AND ENDOSPERM IN SOME SEEDLESS PERSIMMONS 383 
a great variation. A fully developed embryo sac is not always 
formed before the parts begin to disorganize. There is a ten- 
dency toward incomplete organization especially of the antipodal 
cells. The egg apparatus is, of all the parts observed, most fre- 
quently in a state of complete organization but it too may break 
up prematurely. The polar nuclei are often observed in close 
contact but never in a state of fusion. The integuments fre- 
quently push in at this stage and obliterate the cavity of the 
embryo sac without further development of the latter. However, 
considerable endosperm tissue may be produced while at the same 
time the cells of the egg apparatus disorganize. This development 
of endosperm is more rapid in the region of the micropyle and 
may be separated at first from the tissue in the opposite portion. 
At first free nuclei are observed scattered in the peripheral layer 
of cytoplasm, then cell formation begins and gradually extends 
toward the center until the cavity of the embryo sac is completely 
filled with a cellular endosperm tissue. 
It may be of interest also to note that a very defini e nutritive 
jacket layer of cells is organized from the inner integument (FIG. 
3 and 11), and that, although only a small nucellus is formed 
(FIG. 13), a relatively large portion of it is quite persistent. 
It remain$ an open question as to the stimulus causing the 
occasional development of endosperm without fertilization. There 
is the possibility of the presence of pollen tubes in the upper part 
of the pistil, or at least outside of the ovule, but developing too 
late to effect fertilization. Whatever may be the stimulus, a 
well organized endosperm may develop without the initiation of 
an embryo. 
I hope to procure material this summer from trees developing 
fertile seeds in order to trace the embryology. Experimental 
plantings show that a large per cent of the well developed seeds 
germinate readily. 
NORTHWESTERN UNIVERSITY, 
Evanston, ILL 
4 
