THE SMALL-MAMMAL PROBLEM 747 
Firstly, we must learn to deny unnatural shelter and food 
supplies to small mammals. Secondly, we must not give 
them an unnatural security from their enemies in the open 
country. 
All new buildings in town or country should be of rat-proof 
construction ; especial attention should be given to buildings 
destined to house great quantities of foodstuffs. Among 
existing buildings, those which are rat-ridden should either 
be disinfested and repaired, or else they should be demolished. 
Many a house at present infested could be cleared of rats and 
mice, and made practically safe from further invasion were two 
or three drains properly sealed, or a broken ventilator or so 
repaired. ‘ Shelter” and “food,” of course, must be construed 
liberally ; for the dump of rubbish standing for years on a piece 
of waste ground, or the unguarded sewer and its filthy contents, 
may provide small mammals with both palatial accommodation 
and regal fare. At all times special attention should be given 
to the protection of human food supplies, to stables and other 
places in which domestic animals or their foodstuffs are kept, 
and to the collection and disposal of garbage. There are 
many ways of protecting cornstacks and the like from the 
attacks of rodents, and the adoption of one or other of such 
means should be insisted upon. 
The effects of all such preventive measures should be 
carefully watched and studied. As described above, many 
modern buildings, successfully resisting the attacks of 2. 
norvegicus from below, have been invaded by &. rattus 
from above. Had the telephone cables been provided with 
rat guards, no trouble with &. radtus would have ensued. 
At every step, therefore, we must be on the alert, lest in 
shutting the door to one species, we open a way for another. 
Although we can and should protect such things as farm 
buildings and cornstacks, it is impossible to make the open 
fields rat or mouse proof. And if we were able to do such 
a thing, it might be very far from advantageous to attempt 
it. But Nature has provided the best means of keeping the 
rodent population in control in the open country—a means 
which will not fail us if we do not seek its destruction, and 
if we do our part by denying, as far as may be, all unnatural 
