Plate IV. 



All the figures refer to Zannichellia palustris L. 



Fig. 8i. Nearly median longitudinal section through the stem-apex; X 70. 

 The actual apex, ;r, was not included in the section, but its position is indi- 

 cated by the dotted line; sh, the sheath below the node; /', /', the two "spathe 

 leaves;" /, lacunae in the leaves; $, female flowers; (J, male flowers; 57, 

 squamulae intra vaginales; x' , apex of a lateral branch. 



Fig. 82. Transverse section of the terminal buds. The leaves are num- 

 bered; otherwise the lettering as in fig. 81. 



Fig. 83. Longitudinal section of stem-apex; X 200. The apex, x, was 

 divided into two parts, only one of which shows in the section. 



Fig. 84. Transverse section of the staminal primordium; X 400. 



Fig. 85. Longitudinal section of the stem-apex after its division into the 

 carpellary branch, ? , and the secondary stem-apex, v; X 200. 



Figs. 86-88. Development of the stamen seen in longitudinal section; X 

 200. 



Fig. 89. Transverse section of an older anther. 



Fig. 90. Longitudinal section of an older stamen, showing the peculiar 

 terminal appendage; X 60. 



Fig. 91. Two nearly mature pollen-spores. In b, the primary nucleus is 

 dividing. Two free nuclei, k, are shown, derived from disintegrated arche- 

 sporial cells; X 400. 



Fig. 92. Longitudinal section of young female inflorescence, showing the 

 dichotomy of the plerome; X 400. 



Fig. 93. A similar section through the margin of an older inflorescence, 

 showing the ovular rudiment, o, and the subtending carpellary leaf, c. 



Figs. 94-96. Early stages in the development of the female flower in 

 longitudinal section; X 400. o, ovular rudiment; far, carpel. 



Fig. 97. Section of the young ovule, showing the primary archesporial 

 cell; X 400. 



Fig. 98. Cross-section of a young flower; X 400. car, Carpellary leaf; ty 

 the primary tapetal cell. 



Fig. 99. Longitudinal section of an older flower; X 150. 



Figs. 100, loi. Longitudinal section of ovules, showing the later divisions 

 in the archesporium; t, tapetum. 



Fig. 102. An older ovule, the nucleus of the embryo-sac already divided; 

 X 400. 



Fig. 103. Longitudinal section through the inflorescence, showing its con- 

 nection with the main axis; sh, the involuere. 



