Bower . — Studies in the Phytogeny of the Filicales. 323 
large cells of the annulus, is according to the type for Gleichenia , but that the inner sporangia do 
not maintain that regularity, x ioo. 
Fig. 34. The very characteristic spores of Lophosoria , and their germination, x 250. 
PLATE XXXVI. 
35- A young prothallus of Lophosoria , which has just begun to form antheridia. x 66. 
Fig. 36. The venation of the fertile pinna of Struthiopteris orientalis ; the dots on the veins 
indicate the receptacles. Enlarged. 
Fig. 37. Vertical section of a sorus of Struthiopteris orientalis , from a plant grown in the 
Glasgow Botanic Garden. It shows the indusium covering the basipetal sorus, and itself overlapped 
by the leaf-margin. Note that the vascular strand extends beyond the insertion of the receptacle, 
x 160. 
Fig. 37 bis. Another example, showing clearly the basipetal sequence of the sporangia, x 160. 
Fig. 38. a , b. Vertical sections of the sorus of Cystopteris fragilis. a cuts the leaf- lobe trans- 
versely ; b cuts it longitudinally, so as to include the leaf-margin. The first sporangium appears 
in a median position, terminal on the convex receptacle, x 250. 
Fig. 39. Section of an older stage cut as in Fig. 38 a, or as indicated by the line crossing Fig. 
40 vertically. The median sporangia, which are the oldest, have been cut though their stalks only ; 
the lateral ones, being shorter, have been cut through their heads. The indusium forms an efficient 
covering, x 250. 
Fig. 40. Section of a sorus of Cystopteris fragilis corresponding to that of Fig. 38, but older. 
It shows clearly the basipetal succession of the sporangia, but only on one side of the receptacle, 
x 250. 
Fig. 41. Vertical section through a sorus of Woodsia obtusa , showing the vascular supply into 
the receptacle, the basal indusium, and the basipetal succession of the sporangia, x 160. 
Fig. 42. Very young sorus of Woodsia hyperborea , seen in surface view. Sp. indicates the 
sporangia, id. indicate the beginnings of the indusium. From a drawing kindly lent by Professor 
von Goebel. 
Fig. 43. a , b, c. Transverse sections of the stalks of sporangia of Hypoderris , showing the 
differences which exist in complexity of the stalk, which shows sometimes three, sometimes two, or 
one cell in section, x 250. 
Fig. 44. b, c. Three types of sporangia, showing different segmentations, which tally with 
what is seen in Fig. 43. x 250. 
Figs. 45 and 46. Vertical sections of young sori of Nephrodium Filix-mas , cut in a direction 
corresponding to that of the figure (38, b) of Cystopteris fragilis. The similarity of structure is obvious, 
X 250. 
