OF CERTAIN TERMITE NESTS. 211 



remark that the mechanical elements (in the comb) occur 

 sometimes in discs as' if they had been arranged by an expert 

 anatomist. 



Considering the deptli from which these agarics arise, and 

 the number which commence development on a single comb, 

 it might be thought an easy matter to obtain a series of 

 stages showing all the different periods of growth. This how- 

 ever is not possible. It is extremely rare to find a specimen 

 which has only partly penetrated the soil. One appears 

 above ground and all the rest remain aborted in the chamber, 

 and there is no way of ascertaining that a comb has reached 

 the agaric-producing stage until this solitary mature agaric 

 is fully expanded. The surrounding combs may then con- 

 tain eggs and larvae, and show no trace of an agaric. Digging 

 up nests at random has never yielded any results as far as the 

 agaric is concerned. 



In the mound of hyphae which grows on and produces an 

 agaric, the apex is continued into the soil as a narrow black 

 thread with a white tip. For a distance of one or two centi- 

 metres it is only one or two millimetres in diameter, but after- 

 wards it increases rapidly to the thickness of the agaric stalk. 

 Unfortunately it has not been possible to obtain stages which 

 would illustrate the development of the pileus : no immature 

 specimen has yet been found between this thin black thread 

 and the stage in which the white portion of the stalk is visible. 

 The youngest available specimen of the latter stage has a black 

 stalk about 18 centimetres long, followed by about 4 

 centimetres of white stalk which tapers to a point capped by 

 a small pileus 1 centimetre in diameter. The pileus fits 

 closely over the apex of the stalk, but the margin is free. In 

 most cases, however, there are a few broken fibrils at the point 

 where the stalk becomes white, and in favourable instances a 

 distinct collar, partly cartilaginous and partly in separate 

 fibres, is present. This, and further evidence which will be 

 adduced later, supports Berkeley's statement that the stalk is 

 covered with a cartilaginous stratum which is continuous with 



