THE ANATOMY AND AFFINITY OF DEPARIA M00RE1, HOOK. 851 



sporangia will suffice to show that the original basipetal sequence has not been 

 obliterated. 



Occasional long-branched hairs are found among the sporangia. The upper lip" 

 of the indusium can no longer be said to be less advanced than the lower lip, and 

 the vascular supply to the relatively massive receptacle contains a copious fan of 

 storage tracheides. 



To one point I would draw particular attention. 



Such a section as that depicted in fig. 34 might, if taken by itself, suggest that 

 while the sorus is clearly marginal, the slight upward tilt is merely accidental and 

 has no bearing on the development, and while a casual examination of mature sori 

 might show that here and there a sorus is slightly tilted — as in figs. 34 and 41, — it 

 might be considered that this point is negligible. But I am of the opinion that the 

 tilting of the sorus is nothing less than the result of the process briefly outlined 

 in the foregoing paragraphs, by which the receptacle has been increased by en- 

 croachment upon the upper surface of the lamina, either so as to provide or 

 maintain a large receptacular surface, or to furnish a greater receptacular mass in 

 which to develop the bundle ending, than would be possible if the upper surface of 

 the lamina were not encroached upon. 



Apart from its initiation and early stages, the development of the superficial 

 sorus agrees in the main with that of the marginal sorus. 



The superficial sorus is initiated by the formation of a small mound of tissue to 

 which at an early stage a procambium strand is directed (fig. 32). The upper surface 

 of the mound becomes the receptacle, and from the sloping sides the indusium arises 

 as a collar (fig. 33). 



The sorus is "mixed," and it is worthy of note that in some cases the median 

 sporangium is so much ahead of its neighbours in development that the basipetal 

 succession is quite pronounced. 



The Sporangium. 



At maturity the sporangium possesses a long stalk, composed of three rows of 

 cells, and frequently bearing a small lateral branch (figs. 34, 37, 38). The capsule is 

 flatly biconvex, and its cheeks vary considerably as to the number and form of the 

 cells which they contain (figs. 35-38). The annulus is perfectly vertical. The 

 number of cells composing it is variable, there being from thirteen to fifteen in- 

 durated, and seven to nine unthickened cells. The stomium is wide and is extended 

 more upon one cheek than the other. The number of spore-mother cells is small, 

 and, as the result of the examination of a large number of sporangia, I concluded 

 that the number is never much larger than twelve. The largest number seen in 

 section of any sporangium was ten, and five to seven were the numbers usually seen 

 in section (fig. 34). The spores are elliptical, and their outer walls usually possess a 

 few ridges with minute, wart-like markings (fig. 39). 



