530 Black . — The Morphology of Riccia Frostii , Aust. 
EXPLANATION OF FIGURES IN PLATES XXXVII AND 
XXXVIII. 
Illustrating Miss Black’s paper on Riccia Frostii. 
Fig. 1-5 were photographed by Miss C. F. Kephart. Magnification 4 diameters. 
All drawings were made with the aid of a camera -lucida. A Zeiss microscope was used with 
apochromatic objectives 16, 8, 4 and 2 mm. n. A 1*30, and compensating oculars 4, 8, 12, and 18. 
The drawings were made on a drawing-board, except those of spermatogenesis, which were drawn at 
table level. 
PLATE XXXVII. 
Fig. 1. Complete thallus, illustrating the typical compact rosette. 
Fig. 2. A thallus, showing irregular growth. 
Fig. 3. A portion of a young thallus, illustrating the prominence 01 individual lobes of the 
plant. 
Fig. 4. Part of a complete rosette, showing how the thallus separates along the original 
divisions. 
Fig. 5. A young thallus, showing irregular growth. 
Fig. 6. Longitudinal section through the growing end of the thallus, showing the wedge-shaped 
apical cell. The origin of the air-chambers is shown in the depressions between the cells, x 500. 
Fig. 7. A transverse section cut through the growing end of the thallus, showing the two 
growing points. The young cell rows are in an inclined, almost horizontal, position, x 250. 
Fig. 8. Cross-section of the mature air-chambers, showing irregular polygonal shape and 
varying size, x 250. 
Fig. 9 a. The stalk mother-cell and the mother-cell of the antheridium proper. Antheridium 
initial projects slightly, x 500. 
Fig. 9 b. Young antheridium, becoming embedded in sex-organ pit. x 500. 
Fig. 10. Young antheridium scarcely projecting above the surface, x 500. 
Fig. ir. Antheridium, showing characteristic tip cells of surrounding filaments, x 500. 
Fig. 12. Cutting off of the antheridial wall, x 500. 
Fig. 13. End cells of filaments adjacent to antheridium have formed a canal leading to the 
antheridium. x 250. 
Fig. 14. First division of primary cell of archegonium. x 500. 
Fig. 15. Two-celled archegonium. x 500. 
Fig. 16. Three-celled archegonium. x 500. 
Fig. 17. Fertilization, x 500. 
Fig. 18. Resting condition of the fertilized egg. x 500. 
Fig. 19. Three-celled embryo, x 500. 
Fig. 20. Small globular embryo, x 250. 
Fig. 21. Oval embryo, x 250. 
Fig. 22. Abnormal sporophyte affected by bacterial invasion, x 500. 
Fig. 23. Sporophyte with spore mother-cells. The amphithecium is partly disorganized, 
x 250. 
Fig. 24. Polar views of the metaphase in a dividing sporophyte cell, showing sixteen long 
curved chromosomes, x 2250. 
Fig. 25. Telophase of a dividing sporophyte cell, x 2250. 
Fig. 26. Resting-stage of the spore mother-cell, showing the prominent nucleolus and the 
delicate network around it. x 1,500. 
Fig. 27. Nucleus of spore mother-cell somewhat elongated, with fibres around the nuclear 
membrane. The chromatin is in irregular lumps, x 1,500. 
