John Hammond 409 



found that early maturity was associated with an excessive amount of 

 fat in pigs. Lucas (54) states that early maturity is associated with en- 

 largement of the trunk together with the attached musculature and with 

 a reduction in size of the extremities. Sanson (55) found that in early 

 maturing animals the growth of the bones in length is arrested by early 

 ossification of the epiphyses — another example of the hastening of age 

 changes in early maturity. Nathusius (5a) concluded from an examination 

 of the skulls of a variety of pigs that in early maturing animals the skull 

 is relatively broad and deep but with late maturing long and narrow like 

 the wild boar, and that these proportions can be affected by nutrition 

 during development. His results have been confirmed by Nehring(57). 

 That early maturity can be hastened by feeding is well shown in 

 Henseler's experiments (58) in comparing the composition of a starved 

 pig with a well-fed one of the same age, the latter not only showing a 

 larger hve weight for age but also a higher carcase percentage. Varot 

 and Fleniaux(59) found that in children the method of feeding affects the 

 weight (muscle and fat development) but not the growth in height (bone 

 development). 



Cross-breeding. Table XI shows the average weights and ages of all 

 cross-bred pigs shown during the period 1901-13. These weights have 

 been translated into rates of growth per week and are given in Table XII. 

 As differences in age make it impossible to compare the crosses with 

 averages for pure breeds the weights of each cross have been calculated 

 to common ages and in Table XIII are shown in comparison with the 

 mean weight between the two breeds crossed; it is to this table that 

 reference is made below. 



In several cases the cross is larger than the heavier of the parent 

 breeds — the Berkshire-Middle White and Berkshire-Taraworth crosses 

 are outstanding examples — the same thing occurs in the majority of cases 

 in the Berkshire-Large White cross. In many instances where the differ- 

 ence in weight between the breeds crossed is large, the cross although 

 not actually heavier than the largest parent is heavier than the mean of 

 the parent breeds. In only one case — -the Berkshire-Lincolnshire Curly 

 Coated cross — is the offspring consistently smaller than the mean of the 

 parent breeds. Even if large size is dominant in some cases (although in 

 the majority of animals the first cross is intermediate in size) there is in 

 addition a large increase in size and vigour in the first cross. Whether 

 this is due to additional size factors being brought in as Punnett and 

 Bailey(60) found with fowls or to the recombination of characters eliminated 

 by in-breeding remains to be proven. There is much accumulated evidence 



