228 PETCH : THE FUNGI 



In the simplest form this stroma is an upright rod 5-10 cms. 

 in height and about 2 mm. in diameter. It is at first white and 

 loosely built, but as it increases in length the lower part be- 

 ars greenish and finally black. This change of condition 

 travels upwards until, at the end of a week or so, only the apex 

 is white. It then has a solid white core of parallel hyphae, 

 enclosed by a black outer layer formed by interwoven twisted 

 hyphae ends which give it the appearance of an epidermis with 

 wavy cell walls. In general a few hyphae remain unchanged 

 outside this layer and give the stroma a scurfy appearance. 

 Branched stromata generally occur in abundance, though 

 it sometimes happens that all on a given comb are simple. In 

 most cases in which the comb contained larvae when in the 

 nest, i.e. the brown topped combs, these stromata are weak 

 and divide into a brush of single hyphse at the ends of the 

 branches. As a rule, they do not bear conidia, and soon 

 collapse under their own weight. 



The production of branched stromata appears to depend on 

 the degree of moisture in the comb. If the termites are mere- 

 ly brushed out of the comb as far as possible and the latter 

 placed under a bell jar, the survivors gradually descend to the 

 lower surface and may lie removed at intervals, though the 

 process may occupy a week and the comb in the meantime 

 becomes rather dry. The stromata which develop subse- 

 quently are almost invariably small and simple, and may 

 bear conidia. 



The removal of all the termites m such a way that the comb 

 retains its original degree of moistnr.- is a matter of consider- 

 able difficulty. The use of poisonous gases is undesirable, 

 since it would kill t hem in t he comb : it may be mentioned that 

 carbon dioxide appears to have very little effect. Workers 



• irxl soldiers are fairly easily got lid of. hut the larvae are 

 extremely sluggish and take refuge in the inner passages, where 

 they cannot be reached. Perhaps the hest method is to put 

 the rorul) in the track of a colony oi the small black bungalow 

 ant. "i any of the red ants, and leave it partly covered with a 



