426 Os ter /tout. — On the Life- Hist cry of 
EXPLANATION OF FIGURES IN PLATES 
XX AND XXL 
Illustrating Mr. Osterhout’s paper on the Life-History of Rhabdonia tenera , J. Ag. 
All the drawings were made from nature by the author with the aid of the 
Abbe camera. 
Figs. 1-5 are from material killed in picric acid and preserved in camphor 
water, subsequently infiltrated with gelatine and cut when frozen. 
Fig. 1. Median longitudinal section of a young cystocarp : cpg :, carpogenic cell 
(i.e. auxiliary cell) ; cs., carpostome; st., stalk-cell; b and c, accompanying cells ; 
ee &c., ff &c., gg 8c c., hh &c., ii &c., gonimoblastic filaments proceeding from 
the carpogenic cell and bearing spores at the ends. The spores are shaded in 
the figure : x, x, x, &c., sterile filaments connecting the placenta with the pericarp, 
x 196. 
Fig. 2. Median longitudinal section of frond showing auxiliary cell, cpg , before 
the conjugating-tube has united with it. a, basal cell of branch ; other letters 
as in preceding figure. The carpostome, cs, has just commenced to develop, 
as is indicated by the external depression in the frond, x 274. 
Fig. 3. Median longitudinal section of frond. The auxiliary cell, cpg, has cut 
off a small cell (shaded in the figure) which has divided into four. Another, a 
sister-cell, which lies above it and which has not yet divided, is not shown in the 
figure. The carpostome, cs, is further developed than in the preceding figure. 
The cells external to the cell h (which lies under the cells immediately surrounding 
it in the figure) have died away, causing a depression in the surface of the frond. 
The pericarp consists of a few radiating filaments of cells. Letters as in Fig. 1. 
x 384. 
Fig. 4. Median longitudinal section of frond. The small cells which are shaded 
in Fig. 3 have begun to grow out into gonimoblastic filaments which here consist 
of a mass of small crowded cells (shaded in the figure). The carpostome, cs, and 
pericarp are further developed than in the preceding figure. Letters as in Fig. 1. 
X384. 
Fig. 5. Median longitudinal section of frond. The gonimoblastic filaments 
(shaded in the figure) begin to show their filamentous character. The carpostome, 
cs, has the position and shape which it possesses in the mature cystocarp. Letters 
as in Fig. 1. x 384. 
Figures 6-9 are drawn from living material. 
Fig. 6. Transverse section of frond, showing mature tetrasporangium with 
a thinner inner wall and a thicker outer one. The transverse lines in the tetra- 
sporangium indicate the surfaces of contact of the spores, which are masses of 
protoplasm not separated by cell-walls, x 280. 
Fig. 7. Transverse section of frond, showing the spores dividing inside the 
tetrasporangium. x 2 So. 
Fig. 8. More advanced stage of same ; the lines of separation between the four 
masses of cells resulting from the division of the tetraspores are no longer visible, 
x 280. 
