574 FKOM NORTH POLE TO EQUATOR. 



Note 38, p. 170. Heat in the Desert. 



50 Celsius, or Centigrade = 122 Fahrenheit. Temperatures of 121, 

 122, 133 Fahr., and so on, have been repeatedly recorded in the desert. 

 Solymos, in his Desert Life, notes 115 Fahr. in the shade as the maximum 

 for his year. He also calls attention to the frost and ice ! " Duveyrier 

 registered frost twenty-six times between December and March in the 

 plains of the Central Sahara." His picture of the desert- well is much less 

 optimistic than Brehm's. 



Note 39, p. 173. The Termites. 



Termites or "white ants" are very characteristic, wood -eating insects of 

 tropical Africa and other warm countries. Though not related to the true 

 ants, they have somewhat similar social organizations. 



The reader will be rewarded who turns to Prof. Henry Drummond's 

 Tropical Africa, where there is not only a graphic description of the ways 

 of the termites, but an interesting theory of their possible agricultural 

 importance. As they avoid the light, and travel on the trees only under 

 cover of their tunnels of finely-comminuted and cemented earth, they must 

 be continually pulverizing the soil. When rain-storms come this fine dust 

 is washed from the trees, and some of it may go to swell the alluvium of 

 distant valleys. Hence the termite may be, like the earthworm, a soil- 

 maker of considerable importance. Mr. H. A. Bryden, in his Gun and 

 Camera in Southern Africa (London, 1893), writes as follows of the termites: 

 " Our cases, portmanteaus, &c., were arranged round, but not touching the 

 walls. Every article reposed on glass bottles, as the only known protec- 

 tion against the depredations of white ants. . . . They will eat large 

 holes in a thick tweed coat in one night, and anything softer than metal 

 left to their tender mercies for a night or two is irretrievably ruined. . . . 

 If the huts are inspected every few days, the tunnels of self-made mortar 

 can be swept away, and the depredator kept at all events to the flooring. 

 . . . Most housewives have, at least once a year, to institute a crusade 

 against the marauders, dig up the flooring, and attempt to find the queen. 

 If the queen-ant can be successfully located and dug up, the nuisance is 

 ended ; the rest of the ants, bereft of their sovereign, at once quit the 

 building, and for a season trouble no more. ... In the forests to the 

 north and west the mischief done by these insects is enormous. The tree 

 is attacked, the tunnels are run up along the bole, the wood is pierced and 

 riddled, and the work of destruction is soon completed." 



There is, however, a lack of precise observation as to the extent to which 

 termites attack trees which are altogether sound and living. In great 

 measure they merely hasten and complete a destruction for whose initiation 

 they are not responsible. 



Note 40, p. 173. Summer Sleep. 



Summer-sleep in torrid regions, affecting a few fishes, amphibians, and 



