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ECONOMIC ZOOLOGY 



A rat may bring forth from three to a dozen litters of young a year, 

 with from six to twenty in a litter, averaging perhaps ten per litter. 

 At this rate, and with the females reaching sexual maturity in three or 



four months, it will be seen how, under favorable conditions, a locality 

 may, in a short time, be simply overwhelmed with the pests, so that the 

 most vigorous remedial efforts must be exerted to stem the tide. 



