700 Sargant.—Recent Work on the Results 
very welcome suggestion, and I hope it will find favour with 
botanists. 
Le Monnier (29), on the other hand, suggested in 1887 that 
the fusion of the polar nuclei ought to be considered as an 
act of fertilization, and the tissue derived from it as a second 
embryo modified to serve as a food-tissue for the embryo 
regularly derived from the fertilized egg-cell. 
The fact that a generative nucleus takes part.in the forma¬ 
tion of the original endosperm-nucleus certainly strengthens 
the view that this nucleus is formed by an act of fertilization. 
Whether the tissue derived from its repeated division is 
morphologically a second embryo or not is a question of 
race-history. It must be settled by purely morphological 
evidence—by the search for intermediate forms, which may 
either give some conception of the stages through which such 
a twin-formation passed before it assumed its present aspect, 
or may link the endosperm with a reduced prothallus. Treub 
(40, p. 194 ) has given good reason for supposing that a con¬ 
siderable number of nuclei are formed in the embryo-sac of 
Casuarina before fertilization. It is of the first importance 
that we should know the details of the process of fertilization 
in this genus. Unfortunately the difficulties of observation are 
great (Treub, 40, p. 399 ). They may possibly be overcome by 
the application of the most recent fixing and staining methods. 
In Peperomia , Johnson (27) has found a fusion of six nuclei 
to form the primary endosperm nucleus. His work and that 
of Campbell (21) is discussed by Strasburger, who is inclined to 
consider the structure of this embryo-sac as derived from the 
normal structure rather than as primitive. The examination 
of more allied forms might throw light on the question. 
The embryo-sac of the Amentiferae shows the usual ar¬ 
rangement of nuclei before fertilization. (Nawaschin, 33, 34, 
35, 36, and Benson, 17). Much in the development of the 
embryo-sac, however, shows a primitive structure, and it would 
be very desirable to have fuller details of the act of fertilization 
itself. 
Strasburger (11, p. 310 ) has suggested that the Angiosperms 
