1gtt] SMITH—CLINTONIA 215 
MCALLIsTER’S (7) discovery of temporary walls separating the first 
four nuclei of the embryo sac of Smilacina, which otherwise resem- 
bles Lilium, is strongly confirmatory of this interpretation. Though 
the results of the present paper have no direct bearing upon this 
question, it may be pointed out that in Clintonia and the Onagra- 
ceae we see for the first time a mature gametophyte of four nuclei 
proceeding from an indubitable megaspore; and the occurrence 
in the Penaeaceae (STEPHENS 12) and Euphorbia procera (Mopt- 
LEWSKI Q) of four symmetrically placed groups of nuclei, each 
group similar in appearance to the gametophyte of Clinionia, 
certainly suggests a similar origin for each group. No case is yet 
known of a 16-nucleate embryo sac derived from one of four 
megaspores. In Peperomia (BROWN 1) and the Penaeaceae (12) 
there are no tetrads, and reduction occurs in the embryo sac. 
In Euphorbia procera the history has not been traced back to the 
mother cell. In Gunnera' also (MopiLewskr 8, Ernst 5) there 
are no tetrads. The case of Pandanus (CAMPBELL 3) offers some 
difficulty; the embryo sac is said to be one of three sporogenous 
cells (presumably megaspores). But CampsBett did not obtain 
evidence where the reduction divisions occur, and the view that in 
the group of three “‘sporogenous cells” the upper two are parietal 
cells rather than megaspores is a fair inference from his figures and 
data. The point certainly needs further investigation. 
Clintonia, Eichhornia (SmMiItH 1898), Avena (CANNON 1900), 
and Asperula (LLoyD 1902) give us examples of four megaspores 
in one sac, and in Crucianella LLoyp (1902) found all four mega- 
spores germinating within the one wall. No one doubts that these 
are megaspores, simply because three of them or their products 
disintegrate. But surely the weightier evidence is that of chromo- 
some reduction, and this applies equally to Lilium, Peperomia, 
etc. This is the position taken by Coutter (4). He maintains 
that in the genesis of the angiosperm embryo sac ‘the essential part 
of the process is found in the first two divisions,” and he adds 
““megaspores, at least their nuclei, cannot be omitted.” BRowNn 
(2) thinks we cannot make chromosome reduction the sole test of 
‘ ERNST understands SCHNEGG (1902) to assert the occurrence of tetrads in 
Gunnera Hamiltoni, but the latter author does not figure tetrads nor use the word, 
and it seems probable his “ Viertheilung”’ refers to nuclear and not to cell division. 
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