179 BOTANICAL GAZETTE [MARCH 
Treub’s Casuarina agrees with Salix in that its antipodals are 
also hard to find. Treub states that they do not exist, and in 
claiming the development of an embryo sac without antip- 
odals he has certainly given us something unique. Treub’s 
main work was upon the sporogenous tissue, sterile macro- 
spores, and chalazogamy, and his results here are unquestionable ; 
but it might be worth while to have the development of the 
macrospore worked out in detail. 
With the exception of the problematical case represented in 
jig. 37, nothing was observed which would suggest the forma- 
tion of endosperm before the entrance of the pollen tube. In 
Casuarina, as described by Treub (22), the endosperm is formed 
before fertilization, and does not have its origin in a primary 
endosperm nucleus formed by fusion of polar nuclei. If Casua- 
rina has no primary endosperm nucleus, the mode of origin of 
the endosperm is also unique. The formation of endosperm 
before fertilization is not at all unusual, if fertilization be defined 
strictly as the fusion of the sex cells. In general the division 
of the primary endosperm nucleus precedes the division of the 
oospore as frequently as it follows, and it is not exceptional to 
find two or four nuclei in the endosperm before the division of 
the oospore, but in all these cases the formation ot endosperm 
seems to be initiated through the influence of the pollen tube. 
Since Treub’s figures show the pollen tube within the macrospore 
he may have merely an unusual amount of endosperm formed 
before the fusion of the sex cells. It is certainly true that Casua- 
rina has a more extensive endosperm formed before the division 
of the oospore than has yet been described for any —_— angio- 
sperm, Myrica somewhat approaching it in this respect Unfor- 
tunately I have had no opportunity to examine any preparation 
of Casuarina. 
RECAPITULATION AND SUMMARY. 
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