THE TSETSE POISON. 51 



yards distant, contained not a single specimen. This was 

 the more remarkable as we often saw natives carrying over 

 raw meat to the opposite bank with many tsetse settled 

 upon it. 



The poison does not seem to be injected by a sting, or by 

 ova placed beneath the skin; for, when one is allowed to 

 feed freely on the hand, it is seen to insert the middle prong 

 of three portions, into which the proboscis divides, some- 

 what deeply into the true skin ; it then draws it out a little 

 way, and it assumes a crimson color as the mandibles come 

 into brisk operation. The previously-shrunken belly swells 

 out, and, if left undisturbed, the fly quietly departs when it 

 is full. A slight itching irritation follows, but not more 

 than in the bite of a mosquito. In the ox this same bite 

 produces no more immediate effects than in man. It does 

 not startle him as the gad-fly does ; but a few days after- 

 ward the following symptoms supervene : the eye and nose 

 begin to run, the coat stares as if the animal were cold, a 

 swelling appears under the jaw and sometimes at the navel; 

 and, though the animal continues to graze, emaciation com- 

 mences, accompanied with a peculiar flaccidity of the rnus-' 

 cles, and this proceeds unchecked until, perhaps months after- 

 ward, purging comes on, and the animal, no longer able 

 to graze, perishes in a state of extreme exhaustion. Those 

 which are in good condition often perish soon after the bite 

 is inflicted, with staggering and blindness, as if the brain 

 were affected by it. Sudden changes of temperature pro- 

 duced by fails of rain seem to hasten the progress of the 

 complaint; but, in general, the emaciation goes on unin- 

 terruptedly for months, and, do what we will, the poor 

 animals perish miserably. 



When opened, the cellular tissue on the surface of the 

 body beneath the skin is seen to be injected with air, as if 

 a quantity of soap-bubbles were scattered over it, or a dis- 

 honest, awkward butcher had been trying to make it look 

 fat. The fat is of a greenish-yellow color and of an oily 

 consistence. All the muscles are flabby, and the heart 



