Departmental Activities. 206 



itself in the blood of the wild host within a certain time if not 

 rejuvenated by passing through the insect host. 



If this were not so, practically all the wild hosts of the 

 trypanosome would show constant infection ; this, available evidence 

 goes to indicate, is not the case. Moreover, the removal of such 

 animals from fly-belts to all parts of the world to be enclosed in 

 zoological gardens, in close contact with susceptible animals, might 

 well have led to a multitude of sporadic outbreaks of nagana. Every- 

 where it must be admitted there are biting flies capable of trans- 

 mitting infection mechanically, just as they do in the areas where 

 the disease is epizootic in Zululand to-day. At least sixteen zebras 

 have been sent oversea from the Umf jlosi fly-belt in recent times, 

 and animals are obtained indiscriminately, irrespective of fly-belts, 

 for zoological gardens. 



Only experiment can demonstrate whether or not the trypanosome 

 exhausts itself relatively quickly in its wild mammalian host in the 

 absence of tsetse. And, should this prove to be the case, it may have 

 a most important bearing on the practical control of nagana, which 

 would then resolve itself into a limited destruction of the wild 

 mammalian reservoirs that frequent the contracted winter breeding 

 grounds of the fly. 



Wintering of G. pallidipes. — It has recently been possible to 

 demonstrate that this species continues to propagate throughout the 

 winter, and that it does not hibernate. The period of gestation and 

 the pupal period are, however, lengthened out to as miich as twice 

 the lengths of the summer periods. 



Fly Hosts. — As regards the favoured hosts of G. pallidipes, it 

 may be said that much seems to depend upon bulk, gregariousness, 

 complacency, and hairiness. It has been observed that the larger the 

 animal the greater the number of flies attracted to it, and that a 

 troop is more attractive than a single animal. Further, slow-moving 

 and browsing animals seem to collect more flies than fast-moving 

 ones. Complacency under attack seems to go with the thicker hide 

 and the accompanying paucity of hair. 



BOTANY. 



The Spanish Reed {Arundo donax) is a tall reed grass, with stout 

 stems from \ to over 1 inch in diameter, massive creeping root stock, 

 and heads of feathery flowers. There has recently been a demand from 

 overseas for these reeds for use in the manufacture of musical instru- 

 ments and of fishing rods. Samples sent to the Imperial Institute 

 were submitted to firms of manufactures, and were reported on favour- 

 ably, and a small trial consignment has been sent to England. 



It is now a question of transport charges, etc., as to whether the 

 export of these reeds will be a paying proposition. They grow freely 

 enough in the warm moister parts of the Union, and there is little 

 labour attached to the harvesting of them; careful selection, cutting 

 at the right time, and baling them in bundles of about 200 lb. each, 

 is about all that is required. Of course, the market is not a very 

 extensive one, the quantity of these reeds used in the trade being 

 com parati vely sm all . 



