Chap. III. THEIR VARIATION. 87 



ence, no doubt, may be due to descent from primordially 

 distinct species ; but we may feel sure that there has been in 

 addition a considerable amount of variation. Even during the 

 Neolithic period, the domestic cattle were not actually identical 

 with the aboriginal species. Within recent times most of the 

 breeds have been modified by careful and methodical selection. 

 How strongly the characters thus acquired are inherited, may 

 be inferred from the prices realised by the improved breeds ; 

 even at the first sale of Colling's Short-horns, eleven bulls 

 reached an average of 214?., and lately Short-horn bulls have 

 been sold for a thousand guineas, and have been exported to all 

 quarters of the world. 



Some constitutional differences may be here noticed. The 

 Short-horns arrive at maturity far earlier than the wilder 

 breeds, such as those of Wales or the Highlands. This fact 

 has been shown in an interesting manner by Mr. Simonds, 57 

 who has given a table of the average period of their denti- 

 tion, which proves that- there is a difference of no less than six 

 months in the appearance of the permanent incisors. The 

 period of gestation, from observations made by Tessier on 1131 

 cows, varies to the extent of eighty-one days; and what is 

 more interesting, M. Lefour affirms " that the period of ges- 

 tation is longer in the large German cattle than in the 

 smaller breeds." 58 With respect to the period of conception, it 

 seems certain that Alderney and Zetland cows often become 

 pregnant earlier than other breeds. 59 Lastly, as four fully- 

 developed mammae is a generic character in the genus Bos, 60 

 it is worth notice that with our domestic cows the two rudi- 

 mentary mammas often become fairly well developed and yield 

 milk. 



As numerous breeds are generally found only in long- 

 civilized countries, it may be well to show that in some 

 countries inhabited by barbarous races, who are frequently 

 at war with each other and therefore have little free commu- 



5 7 < The Age of the Ox, Sheep, Pig,' vations from Youatt on Cattle, p. 527. 

 &c, by Prof. James Simonds, published ™ ' The Veterinary/ vol. viii. p. 681, 



by order of the Royal Agricult.Soc. an d vol. x. p. 268. Low's ' Domest. 



"'Ann. Agncult. France,' April, Animals of Great Britain,' p. 297. 

 1837, as quoted m « The Veterinary,' eo Ml , 0g leby, in < Proc. Zoolog. Soc.,' 



vol. xn. p. 725. I quote Tessier's obser- 1836, p. 138, and 1840, p. 4. 



