as Enemies of Mankind. 



6i 



Summary of possible Eat Population on December 31st, 1918 :- 



Breeding Pairs. 



Survivors ol" Capital Stock . . . 500,000 

 Generation 2, Litter 1 . . 1,291,674 



2,400,000 

 3,050,000 

 3,150,000 

 2,800,000 

 1,900,000 

 3,600,000 

 3,600,000 

 3,080,000 

 3,900,000 

 3,700,000 

 3,900,000 

 4,270,000 



Pairs with a chance of breeding possibly 



living on December 31st, 1918 



2, , 



, 2 . 



2, , 



, 3 . 



2, , 



, 4 . 



2, , 



, 5 . 



2, , 



, 6 . 



3, , 



, la . 



3, , 



, Ih . 



3, , 



, Ic . 



3, 



, 2a . 



3, , 



. 26 . 



3, 



, 3a . 



4, , 



, la-a 



41,141,674 



Further, we might expect in early days of January, 1919, litters 

 in Generation 3 as follows : — 



Litters 1^?, 2c, 36, and 4a; from these there might be a further 

 12,358,340 pairs with a chance of breeding. 



Cost of maintaining breeding stock of rats (estimated at \d. 

 per day per rat) 



1918. 



Number of Pairs. 



Cost. 



January 



10,000,000 



£645,000 



February . 



9,208,334 



537,000 



March 



8,416,668 



543,000 



April . 



7,625,000 



476,000 



May . 



6,833,000 



441,000 



June . 



12,874,000 



804,000 



July . 



11,290,000 



730,000 



August 



15,408,000 



981,000 



September . 



13,174,000 



825,000 



October 



15,591,000 



1,007,000 



November . 



17,458,000 



1,090,000 



December . 



17,749,000 



1,145,000 



Total cost 



£9,224,000 



