THE CONDOR 
Vol. XV 
rest. Here they would remain in one spot, often stuck in the mud, until death oc- 
cured. A later symptom of the disease was the development of a whitish-green 
or yellowish diarrhoea. 
During the later stages of the disease the sick birds were often found barely 
holding the head up or with the neck and head extended out upon the ground as 
if dead. While in this languid state, and under conditions of great heat and dry- 
ness, the e}es often became closed due to the formation and drying of matter in 
them, the birds being unable to clean themselves. At times Hesh Hies deposited 
their eggs or larvae in the corners of the eyes, and this doubtless gave rise to the 
opinion on the part of some people that the birds were dying from “worms in the 
eyes”. The mouths and throats of the sick birds were often dry and parched, due 
to cessation of drinking- and feeding. 
When a large flock of ducks on a levee was approached, most of the birds 
would fly off while the invaders were still several hundred yards or a 
([uarter of a mile away. But in these flocks it was nearly always to be noted that 
some of the birds would lose distance and lag behind in the flight, and often times 
r'ig-. 7.i AIain camp (A) from which experimental work was carried on; 
NOTE Kaffir corn field in background 
would alight after a short journey, apparently W'Cak or disinclined to follown 
Other birds would make no attempt to go when the main flock arose. On closer 
approach, these individuals, if on the water, would swum off wuth fair rapidity ; if 
on land, those able to travel w'ould make an effort to get into the water and swim 
off. i\Iany wmuld attempt to fly and. after half swumming and half flying for a 
distance, would gain wing and fly perhajis a quarter of a mile, but more likely 
only a short distance, wfl-ien they wmuld slow^ dowui quickly and flutter onto the 
w^ater. Others would not clear the w^ater at all, but simply race along the top of 
the lake creating- a big commotion, splashing the w^ater violently, often quacking 
loudly as they made every possible effort of head, wungs and legs to get out of 
the w'ay. If the enemy got too close, many wmuld try to dive. Sometimes the)' 
W'ould remain down in the w'ater several seconds, even tw-enty or thirty seconds, 
and then come up in another place several yards away. But the more seriously 
stricken birds wmuld not be able to get much more than the head out of sight. 
Sick birds out upon the lake could nearly ahvays be recognized even at a consid- 
erable distance because they sat low'er in the w'ater, being w-ater-logged, and not 
