70 THE BREEDING OF ANIMALS 



Elephant 20 to 23 months 



Giraffe 14 months 



Dromedary 12 months 



Buffalo . 10 to 12 months 



Camel 13 months 



Jennet . . 12 months 



Seal 11 to 12 months 



Mare 11 to 12 months 



Zebra and Celtic Pony . . . . 334 to 338 days 



Prjewalsky's Horse 356 to 359 days 



Cow 9 months 



Bear 6 months 



Reindeer 8 months 



Monkeys 7 months 



Sheep and Goat 21 to 22 weeks 



Sow 4 months 



Lion 3^ months 



Dog 59 to 63 days 



Fox and Wolf 63 to 63 days 



Guinea Pig 61 days 



Cat 63 days 



Polecat 40 days 



Rabbit . . 30 days 



Squirrel and Rat 28 days 



Mice 21 days 



Small breeds require a shorter time than larger breeds, 

 but this influence may be overcome in breeds which have 

 long been selected for early maturity. According to 

 Youatt, 1 all domestic animals are subject to considerable 

 variation in the length of gestation both above and below 

 the normal period. Tessier 2 has observed a large num- 

 ber of pregnant females among the domestic animals 

 and has reported marked variations in the time required 

 for complete development of the foetus and final expul- 

 sion from the uterus. This authority has reported on 

 582 mares in which the period of gestation ranged from 



1 Youatt, "Cattle," p. 521. 



2 Tessier, "Recherches sur la Duree de la Gestation," Mem. 

 de 1'Acad. des Science, Paris, 1817. 



