276 Cook: EmpBryoLocy oF RHIZOPHORA 
8. During first period of growth about one third of the embryo 
and the greater part of the endosperm are forced out of the embryo- 
sac and lie in the chamber of the ovary. 
g. The second period of growth is confined largely to the 
hypocotyl, but during this time the structure of the cotyledons 
undergoes great modification. 
10. This modification of the cotyledons is undoubtedly for the 
purpose of absorption. 
1. During the third period of growth, the cotyledons elongate 
and the point of union between them and the hypocotyl is forced 
beyond the apex of the ovary. 
The greater part of this work was done in Cuba, but it was 
finished in the laboratory of the New York Botanical Garden. 
The material was collected at Mariel, Cuba, and herbarium speci- 
mens have been deposited in the herbarium of the said garden. 
New YorkK BOTANICAL GARDEN, 
Bronx Park, New York City. 
Explanation of plates 22 and 23 
Figures 1 and 17 are purely diagrammatic, made with the aid of a hand lens. 
Figures 6, 7, and 12-16 are semi-diagrammatic, made with the aid of a very low power 
lens in a compound microscope. Figures 2-5 and 8-11 were made with Spencer's 4/ 
ocular and 2 mm. objective. Figures 24-29 were made with Spencer’s 8/ ocular and 
4 mm, objective. Hie: 18-23 and 30 were made with Spencer’s 8/ ocular and 16 
mm. oil immersion 
Fig. 1. Chom section of ovary showing four ovules. 
Fig. 2, Young ovule showing archesporium and origin of integument. (See 
Fig. 1 
F ig. 3- Young ovule showing archesporium and integuments. (See Fig. 19.) 
Fig. 4. Young ovule showing megaspore and integuments. (See Fig. 20.) 
Fig. 5. Ovule showing i ep of nucellus in the formation of the embryo- 
sac; also the integuments. (See Fig. 21. 
Fig. 6. Embryo-sac containing ies (¢), endosperm (end), somewhat shrunken 
and enclosed in the outer integument (0. 7.), the inner integument having undergone 
disintegration. (See Fig. 8. 
Atrophied ik Same age as figu 
Fig. 8, a-f. Embryo in serial sections find suspensor (sw). Same preparation 
as figure 6, 
Fig. 9. Embryo showing suspensor (sw), prominent cotyledonary structures and 
point of origin of the plumule (.x). 
Fig. 10. Embryo showing irregular cotyledonary structures (cof), plumule (+) 
and vanalar system (vz. s. 
Fig. 11. Tip of cotyle idea structure. About the same age as figure 
Fig. 12. Embryo (em), surrounded by er en son i and snare ‘enclonsa 
in the sac which is composed of the outer integument (o. 
