52 
rapidly shrinking (Pace, Plate XXV, Fig. 43). By the time of 
the fusing of the male nuclei with the egg and the double 
sac-nucleus, only very small remains of both synergids are still 
to be seen (Pace, Plate XXVI, Fig. 45). While this seems to 
be the ordinary course, sometimes the division of the primary 
chalazal nucleus may occur a little bit earlier, even at the 
same time of the division of the primary micropylar nucleus 
(Pacr, Plate XXIV, Fig. 25; Plate XXV, Fig. 27; Plate XXVI, 
Fig. 46). Probably in these cases the fusion of both nuclei 
occurs already before fertilization, leaving a fusion-nucleus 
instead of the usual double-nucleus, as may be derived from 
Pacr’s statement that “one sac indicated the possibility that 
the synergid may fail to unite in the triple fusion,“ or in 
other words, that there was only one nucleus to fuse with 
the second male nucleus. If this record of Cypripedium proves 
to be right, the development of the embryosac corresponds to 
the formula C—Ila—3b. 
Our arguments for this interpretation can be summarized as 
follows: 1. The insufficiency of the interpretation of Miss Pace 
to declare all figures given by her. 2. The details of her figures 
as indicated in my description. 3. The lack of evidence put 
forward in her arguments for the entering of a synergid-nucleus 
in triple fusion and for the chalazal origin of the egg, which 
are both entirely without analogies. 4. The analogies presented 
by Gastrodia, in which both chalazal nuclei fuse soon after 
their formation, by Garcinia, in which they fuse just before 
fertilization and by Moringa, in which fusion takes place after 
fertilization, all three showing the same trinucleate condition 
at the micropylar end. 
As already stated we do not claim to have given a decision, 
this being impossible without reinvestigating the whole material. 
But our suggestion must be admitted as a possible explanation 
and must be rejected on firm grounds before we can accept 
Miss Pacr’s. 
Epipactis pubescens, described by Brown and Snarp (191) 
normally has the ordinary eight-nucleate embryosac. Sometimes 
however the chalazal development stops at the bi-nucleate stage, 
