104 PETCH : THE FUNGI 



they emerge and attack it, building galleries if necessary. 

 Even cow dung on the bare road is devoured by them in this 

 way. 



The construction of these galleries has given rise to the idea 

 that the termites only work in the dark, but anyone who has 

 witnessed the raids of the small red ant (Plagiolepis longipes, 

 Jerdon) on a temporarily unprotected termite colony will 

 agree that the primary object of the galleries is to afford 

 protection from the attacks of other insects. &c. Danger 

 of exposure to a dry atmosphere and consequent too rapid 

 evaporation is quite a secondary matter in most districts of 

 Ceylon. The construction of the nest is sometimes carried on 

 in the full mid-day sunshine. . 



In order to ascertain the effect of this assumed ventilation, 

 a series of temperature observations were made in a mound 

 nest at Peradeniya. The nest chosen (PI. V.) was in every 

 respect suitable for the investigation. It was 2 metres 

 high and 4[, metres in circumference at the base. A sin- 

 gle chimney emerged at about 60 centimetres from the 

 solid apex and rose almost to the level of the latter. This 

 chimney was united to the nest by a solid buttress of clay : 

 its opening, which was oblique and extended almost to the 

 junction with the hill, faced north-east. This construction 

 made it possible to take temperatures in the shadow of the 

 chimney, while the solid buttress diminished the direct heating 

 of the latter. The one chimney was the only possible means 

 of ventilation, and any effect might be expected to be intensi- 

 fied by the size of the nest. The surrounding vegetation was 

 cleared away so as to expose the nest to full sunshine from 7 

 \.m. till shortly after 6 p.m., practically from sunrise to sunset. 

 dings were taken at a depth of I'D ems., i.e., just within the 



body ofthe neat, and with a maximum and minimum ther- 

 mometer at a depth of 80 oms. The results are given in the 

 following table, the temperatures being given in degrees 

 Fahrenheit. 



