Osmunda claytoniana , Z., and O. cinnamomea, L . 93 
Fig. 80. Transverse section of a four-celled embryo of (9. claytoniana , m 
x 350. (The terms, transverse, vertical, and horizontal are used with reference to the 
prothallium. Unless otherwise specified, the drawings are from microtome-sections 
of material fixed with chromic acid, stained in toto with alum- cochineal, and on 
the slide with alcoholic Bismarck-brown.) The basal, median, and octant-walls 
are numbered respectively I, II, III ; Z. is the cotyledon ; st, the stem ; r, the root ; 
and F, the foot; where not specified, the figures are magnified 350 diameters. The 
arrow in drawings indicates the axis of the embryo. 
Fig. 81. Transverse section of an eight-celled embryo, em. 
PLATE VI. 
Figs. 82, 83. Median longitudinal sections of two young embryos of 0 . clay- 
toniana. 
Fig. 84. A.B. Two nearly median sections of a similar embryo of 0 . cinna- 
momea. 
Fig. 85. (1, 2, 3, 4). Four horizontal sections of a somewhat older embryo of 
0 . claytoniana. 
Figs. 86, 87. Median horizontal sections of two similar embryos of 0 . cinna- 
momea. 
Fig. 88. Vertical, and 
Fig. 89. Transverse median sections of older embryos of 0 . claytoniana. 
Fig. 90. A.B.C. Three sections of an embryo of 0 . cinnamomea in which the 
apical cell (r) of the root, was especially well marked. 
Fig. 91. (1, 2). Two vertical sections of a somewhat younger embryo before the 
first segment of the root-cap has been formed. 
Fig. 92. Horizontal section of the cotyledon and foot of an old embryo of O. 
claytoniana. x 300. 
Fig. 93. The apex of the root of the same embryo, x 300. 
Fig. 94. Horizontal section passing through the cotyledon and root of an 
advanced embryo of 0 . cinnamomea. The root is cut somewhat obliquely. 
Fig. 95. Transverse section of the prothallium of 0 . claytoniana , showing the 
lateral position of the embryo {em). x 50. 
Fig. 96. Similar section of an embryo of 0 . cinnamomea showing the calyptra 
{cal), x 100. 
Fig. 97. Transverse section of an embryo of 0 . cinnamomea , passing through 
the cotyledon L and the foot F. The axis of the leaf is here almost at right angles 
to that of the prothallium. 
Fig. 98. Young sporophyte of 0 . claytoniana, still attached to the prothallium. 
x6. 
Fig. 99. Horizontal section of an advanced embryo of 0 . cinnamomea passing 
through the stem-apex ; x, the apical cell of the stem. Alcohol — alum-cochineal — 
Bismarck-brown. 
