204 



















/ 



xr.-. 







Fig. 122. 



Hildenbranciia protolypus, vertical section of old crust showing 

 two conceptacles and limiting lines between the productions of 

 three years. 195 : 1. 



Ill specimens collected in June I 

 found such cavities about 6 cells in 

 diameter and not so deep but that 

 the sporangia reached the border of 

 the aperture (fig. 123 A). The spor- 

 angia in these young conceptacles are 

 of different age. Besides fully devel- 

 oped or two-parted sporangia young 

 ones are found, but also aborted 

 sporangia occur, having sometimes 

 the character of paraphyses (fig. 

 123 .4, B), The production of spor- 

 angia continues a very long time, 

 usually apparently a year (or more ?), while the crust grows gradually in thickness. 

 When the sporangia have been emptied, new ones are produced on the same place 

 from the cells forming the bottom of the cavity, within the emptied sporangial 

 walls or between them, and at the same time the formation of sporangia extends 

 at the sides and upwards on the lateral walls of the 

 cavity, the cells of the vertical cell-rows limiting the 

 cavity at the sides producing sporangia directed obli(|uely 

 or horizontally towards the centre of the cavity, which 

 gradually lakes a nearly orbicular outline. The spor- 

 angia-producing cells divide into a small stalk-cell and a 

 greater outer cell, the sporangium. The stalk-cells of 

 the lateral sporangia seem usually to decay, and the re- 

 placing sporangia must therefore be produced by the 

 cells of cell-rows situated within the stalk-cells. In such 

 a manner the conceptacle increases in transversal out- 

 line, new vertical cell-rows being gradually engaged in 

 the production of sporangia. The parts of the cell-rows 

 which are active in this manner are consumed by this 

 production, and the continuity between the upper part 

 forming the roof of the conceptacle and the under part 

 is thus abolished. The upper part of these cell-rows 

 therefore finally decays, at least in those situated nearest 

 the aperture, where the regular arrangement of the cells 

 is disturbed; the cell-walls swell, and the contents be- 

 come discoloured and degenerate (fig. 125 A). In the 

 peripheral part of the roof, the undermost cells of the 

 interrupted vertical cell-rows often undergo a growth in 

 a transversal direction, in consequence of which the 

 cell-rows become bent inward below (fig. 122). The above 



Fig. 123. 



Hililenbrandia prolotijpiis, vertical 

 sections of young conceptacles. A 

 and 1} from specimen collected in 

 June (near Hcfsn;es), C, from spec, 

 collected in January (Store Belt). 

 560: 1. 



