92 Campbell. — On the Prothallium and Embryo of 
Fig. 46. Similar section of an antheridium of 0 . cinnamomea. The central cells 
are undergoing the last division previous to the formation of the spermatozoids. 
Chromic acid — alum-cochineal — Bismarck-brown, x 650. 
Fig. 47. Two of the central cells from a young antheridium of 0 . claytoniana. 
Chromic acid — alum-cochineal, x 1200. 
Figs. 48-56. Development of the spermatozoids of 0 . claytoniana. x 1200. 
Figs. 52-55, from acetic acid — gentian-violet preparations; 54, Osmic acid — 
methyl-violet ; the other& chromic acid — alum-cochineal preparations. 
Fig. 57 - Free spermatozoid of 0 . claytoniana , killed with osmic acid, and 
stained with methyl- violet, v, the vesicle, x 1200. 
Fig. 58. Spermatozoid of Onoclea struthiopteris , treated in the same way. x 
1200. 
Fig. 59. Vertical microtome-section of a nearly ripe antheridium of 0 . cin- 
namo 7 nea. Chromic acid — alum-cochineal — Bismarck-brown, x 350. 
Fig. 6o s Young antheridium of 0 . claytoniana , with unusually developed pedicel, 
x 600. 
Figs. 61, 62. Development of the archegonium of 0 . claytoniana; 0 , central- 
cell ; /z, neck-canal-cell ; b, ventral canal-cell ; Z, basal cell ; n, n\ nuclei of neck- 
canal-cell. All longitudinal microtome-sections, of chromic acid material, stained 
with alum-cochineal and Bismarck-brown, x 600. 
Fig. 68. Very young archegonium of 0 . cinnamomea , showing the first division 
of the neck-cell. The central cell is also preparing for division, x 650. 
Fig. 69. Section of older archegonium of 0 . cinnamomea , with the neck-canal- 
cell divided into two, c, c' . Chromic acid — alum-cochineal — Bismarck-brown, 
x 600. 
Fig. 70; Vertical section of the base of the archegonium, just before the dis- 
integration of the canal-cells, b , ventral canal-cell ; 0, egg. Chromic acid — alum- 
cochineal. x 650. 
Fig. 71. Ripe egg of 0 . cinnamomea , just before the archegonium opens. 
Chromic acid— alum-cochineal, x 650. 
Fig. 72. Vertical section of a freshly opened archegonium (living). 0, egg; 
h , remains of canal-cells, x 350. 
Fig. 73 - Section through the base of a nearly ripe archegonium, at the time of 
the separation of the polar body (?) p. b , ventral canal-cell. Chromic acid — alum- 
cochineal. x 650. 
Fig. 74. Vertical section of a recently fertilized archegonium, showing the 
spermatozoids within the central cell. Chromic-acid — alum-cochineal — Bismarck- 
brown. x 350. 
Fig. 75 - The basal part of the archegonium shown in Fig. 74, more highly 
magnified. The egg is somewhat shrunken, but a spermatozoid (sp) is clearly seen 
in contact with the nucleus of the egg. 
Fig. 76-78. Fertilization of the egg of 0 . claytoniana. Chromic acid — alum- 
cochineal preparations. 0, the female pronucleus ; sp, sperm-nucleus, x 650. 
Fig. 79. Fertilized egg of 0 . claytoniana , shortly before its first division. Two 
nucleoli are visible in the nucleus ; ar , mouth of archegonium. x 650. 
