214 Cook : DEVELOPMENT OF EMBRYO-SAC AND EMBRYO 
Hegelmaier, in his ‘‘ Untersuchungen tiber die Morphologie der 
Dikotyledonen-Endosperms ” ('7), describes four types of endo- 
sperm development which he designates as: (1) ‘ Allseitig-peri- 
phersche” (¢. g., Adonis, Caltha, Cotoneaster, Malva, Hibiscus). (2) 
“ Peripherisch-simultanen ” (e. g., Bocconia, Scabiosa,, Euphorbia). 
(3) ‘Einseitig peripherischen” (e. ¢., Trigonella, Phaseolus, Fago- 
pyrum). (4) ‘“Endogene”’ (e. g.,Eranthis). In the Nymphaeaceae- 
we apparently have a type intermediate between the third and 
fourth with greater resemblance to the third type, but differing from 
it in the appearance and activity of the lower endosperm nucleus. 
The physiological significance of this nucleus presents a very 
interesting problem which should be considered in connection with 
the function of the antipodals. 
In the case of the Ranunculaceae as described ‘by Coulter (1) 
the very large antipodals indicate some very important function 
which is emphasized by Campbell’s study of Sparganium simplex 
(5) in which he describes a very great increase in the number of 
antipodal cells. Lloyd’s researches on Vaillantia hispida (10) 
seem to throw some light on this problem. He describes the 
behavior of the antipodals, the third and lowest of which form a 
haustorium which projects back into the disintegrating megaspores 
and apparently bearing a nutritive relation to the embryo-sac. 
Guignard in his recent paper on Vaias major (6) describes two of 
the antipodals degenerating and the upper one enlarging long after 
the fertilization of the 6osphere. 
Chamberlain in his paper on Aster Novae-Angliae (3) describes 
and figures a peculiar enlargement of the lower antipodal and 
believes that one of the nuclei represents an odsphere, thus empha- 
sizing Strasburger’s view that the antipodal region is homologous 
with the prothallium of the Gymnosperms. ke: 
Whatever may be the physiological or morphological signifi- 
cance of the antipodals in the plants to which we have just referred 
and whatever it may have been in the past we find many plants to 
which Strasburger’s view cannot be applied. 
In many cases the antipodals are very small and without func- 
tion but we frequently find other structures which are apparently 
performing a similar function to that described by Lloy de 
Vaillantia hispida (10). In Lilium Philadelphicum,(2) Coulter de- 
