and Fertilization in Oenothera . 307 
P. blanda Fisher 1907 
P. galioides „ „ 
P. Langsdorjrfii „ ,, 
Euphorbiaceae: 
Euphorbia procera Modilewski 19C9 
E. palustris ,, 1911 
E . virgata (denied by Modilewski) Dessiatoff ,, 
Acalypha sp. Arnoldi 1912 
Halorrhagidaceae : 
Gunnera Hamiltonii Schnegg 1902 • 
G. chilensis 
G, macrophylla 
Peneaceae: 
Sarcocolla squamosa Stephens 1909 
S.fucata ,, „ 
S. formosa ,, „ 
Penaea mucronata ,, ,, 
P. ovata ' „ „ 
Brachysiphon imbricatus ,, ,, 
Compositae : 
Pyrethrumparthenifolium var. aureum Palm 1914 
The embryo sac of Tanacetum vulgare studied by Palm ( 53 ) is some¬ 
what aberrant from the 16-nucleate condition. The nucleus of the embryo sac 
cell, which is monosporic, divides twice ; the upper two of the resulting nuclei 
also divide twice, while the rest of them undergo one division only, thus 
a 10-nucleate embryo sac results. 
As already mentioned above, those owners of the aberrant embryo sacs 
are herbaceous. An interesting case relating to this fact has been observed 
by Johnson ( 32 ) and Fischer ( 17 ), who state that all the Peperomias hitherto 
studied are herbaceous, while another genus, Piper , so far as examined 
is found to have a 8-nucleate sac, and is a woody climber. On the other 
hand, Modilewski ( 43 , 44 ) and Lyon state that, among fourteen species 
of Euphorbia examined, E. procera and E . palustris are 16-nucleate, while 
the rest possess a normal sac. Such an aberrant case of embryo sac is 
scarcely known to occur in the woody plants already studied of the Euphor¬ 
biaceae. Generally speaking, in the same genus or family, only herbaceous 
plants possess 16- or 4-nucleate sacs, while woody members have a sac 
of the normal type. 
At any rate, tetra- and 16-nucleate embryo sacs are to be regarded 
as representing a derived type, probably caused by mutation and by 
variation, in a certain stage of phylogenetic development. Those herbaceous 
plants which possess such a modified gametophyte must be more evolved 
than others, especially than the woody members in this respect. Moreover, 
herbaceous plants are believed to have been derived from woody ones 
by a gradual decrease in amount of woody elements of vascular bundles, as 
held in Jeffrey’s school, principally basing upon anatomical evidence. Thus 
the view regarding herbaceous plants as derivatives is supported by both 
the gametophytic and sporophytic characters. 
Modilewski 1909 
Ernst 1908 
Samuels 1912 
X 2 
