PHYSIOLOGY OF THE RED MANGROVE. 619 



away, just as described by previous writers, and exposes the pollen 

 in the loculi to the air and contact of insects. The cells here de- 

 scribed with their lignified thickenings are also densely filled with 

 dark-staining protoplasm, similar to those of the petals. According 

 to Warming the cytological development of the pollen grains does 

 not present any unusual feature and the cursory examination of it 

 in the preparation of this paper, which is not concerned with cyto- 

 logical details, seems to confirm Warming's statement. 



The pistil is relatively simple and has a two-celled ovary with 

 the spongy tissue above mentioned beneath it. In each of these 

 two cells there are seen two ovules, one of which becomes a seed. 

 The ovary tapers gradually into the erect and elongated woody style 

 which has a bifid stigma at the tip. The ovary, the ovules, the egg 

 and fertilization apparatus have a very special interest in Rhizo- 

 phora owing to the plant's habit of vivipary. The endosperm itself 

 has been the subject of investigation and considerable specula- 

 tion. Baillon seems to have started the discussion by saying that 

 the embryo is destitute of albumen, but is surrounded by a soft mat- 

 ter which assumed its role. These parts connected with the repro- 

 ductive function are best considered under the next heading. 



Embryology. 



The embryology of the red mangrove has been attacked by sev- 

 eral botanists with more or less success. The study of its vivipary 

 has led up to these detailed studies, which have been made princi- 

 pally by three workers, Warming,^^ 1883, Karsten,'^- 1891, and the 

 most recent by IM. T. Cook,^^ IQO?- The first merely touched inci- 

 dentally on the embryology in as far as it was related to the general 

 morphology. Karsten's work, while more detailed, was undertaken 

 with a view to its relation to vivipary and the ecology of mangroves 

 in the widest sense. Cook's paper summarizes the work of Karsten 

 and while short is very good, but the author himself says that com- 



^1 Warming, Eug., loc. cit., p. 528. 



82 Karsten, G., " Ueber die Mangrove-Vegetation in AIala3-ahn Archipel.," 

 Bibliothcca Botmi'ica, Heft 22, 1891. 



S3 Cook, M. T., " The Embryology of Rkiaophora mangle," Bull. Torr. 

 Bot. Club, Vol. 34, No. 6, p. 271, 1917. 



