394 BIRDS AND BILHARZIASIS. 



times, especially during the summer season, I made examinations 

 of the feet of water-frequenting birds, and in the majority of 

 instances there was no mud on their feet; whilst others had only 

 a film of mud. In a small number of cases the feet had small 

 quantities of mud adhering to them. The ducks and various 

 wading birds are invariably in the water, and when rising the 

 mud is washed from the feet. The birds were shot on the wing 

 immediately after leaving the water. Following this up, I made 

 the most careful examinations of mud scraped from the feet of 

 water-frequenting birds, and uever succeeded in discovering young 

 snails or the ova of snails in this mud. 



I have further evidence to offer of the innocence of birds in 

 the spreading of fresh-water snails. In the vicinity of Port Eliza- 

 beth we have a stream known as Baakens River, which has been 

 infested with bilharziasis for at least half a century. This stream 

 swarms with fresh-water snails. Twenty-five miles from Port 

 Elizabeth by road there is a perennial stream known as Van 

 Staadeus River. A distance of about ten miles separates the 

 upper reaches of this river from the former, while a bird flying 

 in a straight line from the lower reaches of Baakens River would 

 only cover a distance of fifteen miles at most. During three suc- 

 cessive years I visited Van Staadens River during the middle of 

 summer when snails were active and easily procurable. On each 

 occasion I spent three weeks observing the bird life and searching 

 for snails. I failed to discover a single snail in a stretch of river 

 covering two miles. During the same time of year Baakens River 

 was swarming with snails. It is obvious that the water-frequent- 

 ing birds would constantly migrate from the one river to the other. 

 Why then is Baakens River swarming with snails, when accord- 

 ing to the new hypothesis birds are carriers of the eggs and young 

 of snails from river to river ? 



To further strengthen my case in favour of the protection of 

 all water-frequentiug birds, I made a systematic examination of 

 Baakens River for ten miles along its course. The river runs 

 through the city half a mile before discharging its water into the 

 sea. Indians living near the stream keep ducks and geese. I 

 dredged with nets along the portion frequented by these birds, at 

 intervals covering several years, and after two hours' strenuous 

 work some half-dozen snails would be the result. On the con- 

 trary, from beyond this locality for a mile up the river the water 

 is swarming with snails during the summer season. There are no 

 ducks in this portion of the river. Proceeding up stream beyond 

 the city's boundaries, the snails were not nearly so abundant. In 

 some of the upper reaches of the stream in secluded places where 

 human bird slayers seldom penetrate, it was with difficulty I found 

 snails. The conclusions to be drawn from this work are: — 



(1) The ducks and geese devour the snails in the portion of 

 the river frequented by them. 



(2) In the stretch of river near the city which is swarming 

 with snails, wild birds are rarely seen, owing to the proximity of 

 men and the persecution to which the birds are subjected. 



