aS4 SECTIONAL ADDRESSES 



back at least as far as the eighteenth century. The end of the eighteenth 

 and the first half of the nineteenth century was a period of wonderful 

 development in British agriculture, which, in particular, occupied the 

 attention of landowners who in those days carried out a tremendous 

 amount of experimental work. One of the most popular forms of activity 

 was that of endeavouring to substitute'new and improved breeds of live- 

 stock for old local breeds. Replacements did take place in some cases. 

 The old Dun-faced breed was replaced over the greater part of the 

 Highlands by the Black-face ; Cheviots were established in the North 

 of Scotland, and so on. 



But these examples, though important in themselves, were, after all, 

 exceptions to the general rule that in most cases the new introductions 

 either had no effect or merely modified the existing breeds. They did not 

 replace the local breeds. This is the more surprising when we remember 

 that about this time there took place the great change in the relative 

 importance of the functions which the sheep was required to serve. 

 To-day, in Australia and New Zealand, the change over from wool 

 production to meat production involves the replacement of the Merino 

 by a mutton breed of sheep of altogether different origin and character. 

 In this country, in the eighteenth century, the change from wool to mutton 

 did not in the main involve the disappearance of the old breeds. They 

 were modified, but retained their identity. To my mind, this suggests 

 that so far we have failed to fathom the full significance of breed differences 

 and breed distribution. We have paid great attention to meat and wool, 

 but have failed to analyse fully the more basic vital characters on which 

 the survival of semi- wild animals must largely depend. In the case of 

 a sheep which spends its life completely out of doors and is dependent 

 mainly on grass and other semi-natural food, there is almost certainly 

 a delicate adjustment of the animal's physiology to the local environment. 

 Hammond's recently published work on the grovrth of the sheep 

 suggests all kinds of variables which may have to be fitted to corresponding 

 differences of season, amount and composition of food, rate of growth of 

 vegetation, and so forth. Ought we not to regard the animal's general 

 physiology, including this special adjustment, as the element of funda- 

 mental importance on to which the more oljvious characters of meat, 

 wool and milk production have to be grafted ? If so, is it not deserving 

 of much more study than it has hitherto received ? 



It might be urged that great differences of environment also exist in 

 other countries, but that they do not think it necessary to maintain special 

 breeds for small areas. For instance, I imagine that the differences of 

 soil and climate are probably no greater in Great Britain than those in 

 New Zealand, and yet we have more than twice as many breeds. In reply 

 to that, one might say that for all we know there may be as great variation 

 in the sheep stock of New Zealand in fifty years' time as at the present time 

 in this country. 



Another point occurs to one after reading Hammond's book. The 

 first requirement in our ordinary systems of stock improvement is varia- 

 tion. Maximum variation occurs under optimum conditions. In general 

 it may be said that British conditions at their best are optimum conditions 



