OF CERTAIN TERMITE NESTS. 235 



As may be seen, the form of the stroma varies widely : illus- 

 trations of different shapes might indeed be multiplied indefi- 

 nitely, but in general two types may be distinguished — (1) an 

 upright simple stem ; (2) an upright stem branching dichoto- 

 mously at the apex. These may be produced by altering the 

 degree of moisture in the comb if this was in the semi-deserted 

 condition with an abundant growth of mycelium : the brown- 

 topped combs which contain the termites in all stages usually 

 show stromata with less regularity of branching, and these are 

 generally non-conidiferous. A determination of the amount 

 of moisture in fresh combs is desirable, but up to the present 

 has not been found possible. The larvae are extremely slug- 

 gish and take refuge in the central passages, whence they can- 

 not be dislodged. It is therefore impossible to get the weight 

 of a fresh comb without including the larvae at least. 



The conidiophore varies directly with the conditions under 

 which it is grown. That of the pot-grown form is at first sight 

 an Aspergillus, and that of the simple stroma is often only 

 slightly removed from it by the greater development of the 

 four lobes of the simple head. With increase of moisture it 

 becomes branched, but retains the four-lobed head on each 

 branch, though each lobe now bears only two basidia. In a 

 further stage the branches are more regularly dichotomous 

 and diverge at a greater angle, and the separate basidia are 

 also more divergent. Finally, in agar cultivations the conidio- 

 phore becomes altogether irregular, the basidia appearing 

 as somewhat truncate, often crooked, side branches. 



It is noteworthy that the simple stromata have conidio- 

 phores with comparatively simple heads, while the dichotomous 

 stromata repeat the dichotomous branching of their conidio- 

 phore. 



It is not necessary for the development of these conidial 

 forms that the comb should be exposed to light : they will grow 

 equally well in a dark chamber. They are strongly positively 

 heliotropic, and respond readily to slight differences in illumi- 

 nation. 



