ANIMALS AND POISON 75 



the nervous centres till it attacks the lungs. In the 

 water hemlock the poison acts in a different way. 

 Like another and more deadly vegetable poison, 

 strychnine, it causes tetanic spasms. The difference 

 in the nature of the poison contained in plants so 

 closely alike as these two hemlocks may perhaps 

 account for the failure of cattle to know the danger 

 to which they are exposed in eating them. It may 

 well be that one variety, though injurious to man, 

 may not affect cattle. Consequently they might 

 naturally eat without any misgiving the other variety 

 which is deadly to them. 



The sense by which animals detect the presence of 

 a poison is mainly that of smell. They seem to have 

 very little sense of taste upon the palate. But carni- 

 vorous animals have a kind of " half-way " sense be- 

 tween taste and stomach-ache which very soon tells 

 them when they have taken poison or anything likely 

 to disagree with them, and Nature has kindly arranged 

 that they can get rid of it by the throat with very 

 great ease. An extraordinary instance of this was 

 recently quoted in the Country Gentleman. A Scotch 

 keeper had a retriever which he had taught to fetch 

 any object that he had left behind him. One day 

 on the moors in the spring he found that he had 

 left his knife at a place where he had been sitting 

 no great way down the hill, and sent the dog to 

 fetch it. The dog galloped back to the place, 

 and finding the knife, concluded that that was 

 what he was to fetch, and picked it up. So much 

 at least seems certain from the sequel, for when the 



