742 THE SMALL-MAMMAL PROBLEM 



Britain. But such success would not bring with it the real 

 fruits of victory; the small-mammal problem would still remain, 

 demanding urgent solution from the inhabitants of this island. 



The problem in question has arisen in this, as in all other 

 countries, as one of the many far-reaching consequences of 

 human interference with the working of the " Balance of 

 Nature." Small mammals, like humanity, feel the pinch of 

 cold and hunger, or the pain of heat and thirst ; accordingly 

 they welcome shelter from the weather, food and drink in 

 plenty, and security from their foes. Wherever man in the 

 presence of a wild mammalian fauna, contrives a shelter for 

 himself, his goods, or his domestic animals, there will always 

 be a greater or less number of species quick, if not prevented, 

 to enter into an uninvited partnership with him, sharing his 

 joys and, it may be, increasing his sorrows. Among mammals, 

 no doubt, murine rodents show the quickest appreciation of 

 the benefits conferred by unintentional human benefaction ; 

 and they are generally the first wild mammals to become 

 commensal with man. But the power to force an undesired 

 alliance upon careless humanity is not restricted to the Muridse 

 among rodents, nor to the rodents among mammals ; it is 

 shown in various degrees by such different Orders as the 

 Chiroptera, Insectivora, and Carnivora. Individual species 

 belonging to these other Orders like Pachyura gigantea, the 

 Indian Musk Shrew, may become thoroughly parasitic, and 

 acquire greatly extended distributions in consequence. 



Among Muridae, at the present time, three species alone 

 claim so much attention because of their parasitic habits, that 

 there is danger of our overlooking the claims of their rivals 

 in such a connection. Two of the three, the House Mouse 

 and R. rattus, had the good fortune to live originally in the 

 cradle of civilization. Possessing habits which permitted a 

 close association with humanity, they entered the earliest houses, 

 and with civilized man they have spread over the greater part 

 of the globe. The third species, R. norvegicus, is a native of 

 a more remote and desolate region ; widely different in habits 

 from either House Mouse or R. rattus, and habitually shunning 

 the presence of man, it had to wait long for an opportunity 

 of invading Western Europe. Once introduced, it made rapid 



