482 Cauadivn Record of Science. 



tain, and of the hostile foes he is fighting against. 

 Occasionally, however, still another danger threatens 

 the settler. He may inadvertently augment the 

 hostile forces by introdncing powerful enemies from 

 other lands. Plants and animals trained in the fierce 

 struggle that obtains in Europe and Asia often spread 

 to an enormous extent when introduced into the 

 smaller continents, such as America and Australia, as 

 the following instances will show. 



With a view of providing themselves with sport 

 some Australian colonists imported rabbits. To-day 

 thousands of acres of land have been rendered useless 

 for cattle by the. descendants of these rabbits, and 

 hundreds of thousands of dollars have been spent in 

 the attempt to keep the race of rabbits within bounds. 

 The sentiment of some Scotch colonists induced them 

 to send home for some thistle-seed. It fiourished only 

 too well in Australia, but with dire results for cultiva- 

 tion. The English sparrow, as everybody knows, has 

 worked great destruction amongst our native song 

 birds, and one has only to see in the spring the fields 

 in the Island of Montreal covered with the English 

 ox-eye daisy to realise the danger of introducing 

 European wild plants into this country. 



Once indeed a visitor from the j^ew World turned 

 the tables on the Old World population. The common 

 water-weed of the St. Lawrence, Anacharis, was culti- 

 vated in a tank in the Botanical Garden at Cambridge, 

 England, where it flourished luxuriantly. The pro- 

 fessor of botany, with a carelessness unworthy of his 

 calling, gave orders that some of it should be thrown 

 into the brook which ran outside the garden. This 

 was done, and the Anacharis grew luxuriantly in tlie 

 brook, from which it reached the river Cam, and from 



