196 Transactions British Mycological Society. 



thick and composed of somewhat loosely intertwined, much 

 branched hyphae (lig. 9). As the plant increases in diameter the 

 cortex becomes slightly thinner, owing to the hyphae of which 

 it is composed becoming more closely compacted; otherwise 

 little change occurs until the plant appears on the surface. As 

 portions become exposed to the light, colour appears in them, 

 due to the formation of the pigment granules already men- 

 tioned. Little change then takes place until the plant is about 

 half-grown, but from this stage until maturity practically all 

 increase in diameter is due to growth of the inner portion of the 

 peridium, with the formation of tramal plates. 



Development of the gleba and trabeculae. The dome-shaped zone 

 of cavities encloses a column of densely woven, vmdifferentiated 

 hyphae, which gives rise to the trabeculae and sterile basal disc 

 (fig. 9) . The cavities of this zone are at first few in number and 

 are large and irregular in size and shape. They are separated 

 from one another by thin plates formed of closely compacted, 

 parallel hyphae. Scattered papillae, often arranged in small 

 ridges, arise on these plates, and on these, solitary scattered 

 basidia appear, bearing from one to four spores (figs. 1-3). No 

 definite hymenium is present, nor does it appear until the plant 

 has reached a much later stage of development. The cavities 

 slowly increase in number and size as the plant increases in 

 diameter, and basidia become more numerous, although as yet 

 still confined to scattered papillae. These large and irregular 

 cavities continue to appear until the plant has reached the 

 surface of the ground, the plant at this stage being about 

 7x5 mm. The greater part of the gleba is seen to be occupied 

 by them, save for the central column of sterile tissue. When the 

 plant reaches the surface, a second phase of development com- 

 mences. Up to this time growth has been slow, and internal 

 differentiation but little advanced. Now, however, considerable 

 growth occurs in the trabeculae and tramal plates ; they increase 

 considerably in thickness, and numerous branches are given 

 off from them. These divide the large cavities into smaller ones 

 (fig. 11), and at the same time lacunae appear in the plates and 

 smaller trabeculae, so that in a short space of time the whole 

 zone, formerly occupied by a few large cavities, is broken up 

 into very numerous smaller ones (fig. 12). As these lacunae 

 appear their walls are lined with a definite hymenium, the 

 basidia bearing six spores, the normal number of the mature 

 plant. Growth of tramal plates and trabeculae continues in 

 this manner for some time until the whole of the gleba, with the 

 exception of those portions occupied by trabeculae and sterile 

 base, consists of minute lacunae and their accompanying 

 hymenium. 



