6182 



Insects. 



peculiarity of the genus, he adds, that — " moreover the bulbous dilated 

 base of the proboscis must evidently play an important part in the 

 economy of the insect, either by giving additional support to the 

 proboscis when in the act of piercing the skin, or by containing 

 powerful muscles for the action of the enclosed setae ; or, as suggested 

 to me by Professor Owen, this dilated base may be analogous to the 

 dilated base of the sling of the scorpion, and like it contain a reser- 

 voir of some powerfully poisonous liquid." The last conjecture sug- 

 gests, most probably, the true solution of the mystery. As gnats or 

 mosquitos are believed to instil a "droplet" of fluid which occasions 

 the irritation from their punctures, and the purport of which may be 

 to effect some alteration in the blood, adapting it to the minute sec- 

 torial organ of the insect, so, in like manner, the bite of the tzetze is 

 probably envenomed, on which principle only it would seem that the 

 effects produced can be sufficiently accounted for. Mr. Westwood 

 remarks — " The account of the irritating powers of the Glossina given 

 by Captain Vardon is, it is true, not so detailed as could have been 

 desired, but we learn sufficient to arrive at the conclusion that its 

 effects are, to a certain extent, exactly like those of the Tabanidaj ; 

 how far the attacks may be attended with tumours, similar to those 

 produced by the Simulium, and whether a tropical climate may not 

 extend the effects of the attack, producing inflammatory action upon 

 animals perhaps never before in those latitudes, are questions which 

 have yet to be answered. One thing, however, appears to me evident, 

 that the tzetze is no other than the zimb of Bruce (an insect respecting 

 whose real family and even existence so many doubts have been ex- 

 pressed), or at least that that insect is a larger species of Glossina, to 

 whose real habits Bruce has added those of a species of QEstrus." — 

 His figure of it was undoubtedly got up from memory ; as his figure 

 of the Abyssinian rhinoceros is a copy of Buffon's figure of the Indian 

 species, with a second horn added ! And Mr. Westwood remarks 

 that — " It is evident from the note added by the editor of the 8vo. 

 edition, that the drawing of the insect was not a bond Jide one made 

 on the spot, but was manufactured at home." 



Finally, I shall only further cite from Mr. Westwood's paper that — 

 *'The accounts given by Mr. R. Gordon Gumming of the destructive 

 powers of the tzetze fully confirm the opinion here advanced, and 

 prove that although ^its hiie is certain death to oxen and horses,' it 

 causes no dorsal tumours like an (Estrus [modernly so denominated]. 

 ' This hunter's scourge,' he says, ' is similar to a fly in Scotland called 



