102 



Mr. W. Heape. 



is to say, that most twins are produced by the ewes which first come in 

 season, and I interpret that to mean that it is the ewes with the most 

 active and most vigorous generative system, those which are in strong 

 breeding condition at that time, which bear the most twins. It is of 

 interest to note that among Southdown and Hampshire flocks, a com- 

 paratively small proportion of twins are born early in the lambing 

 season, and these breeds produce the smallest percentage of twins. 



The effect of locality upon the fertility of a breed is worthy of con- 

 sideration, and statistics are given in Table V to illustrate this point.* 

 In considering these figures, numerous other important influences 

 must be borne in mind, which the information at my disposal makes it 

 impossible to dissociate from locality ; and in all cases, except those of 

 the Shropshire and Lincoln breeds, where a wide difference in fertility 

 is shown in different districts, it is possible that the variation in 

 fertility may be due to one or other or all of these various influences, 

 apart altogether from locality. 



The fertility of a flock is greatly influenced by its management and 

 by the conditions under which it lives ; the condition, kind, and 

 amount of food available before tupping time will affect the condition 

 of the ewes and the percentage of twins subsequently born ; the season 

 may be more favourable for tupping or for lambing in one district 

 than in another ; cold, rain, or want of rain, will affect the feed, the 

 ground, and the ewes themselves ; while, owing to mortality among 

 ewes during lambing or at other times in the preceding year, the 

 flocks in one district may consist of a larger proportion of shearling 

 ewes than the flocks in another district, and this may affect the birth 

 rate of a flock. 



These and numerous other such influences, combined with the undue 

 proportionate value of excessive loss or fertility in one flock, where 

 only a few are kept in a district, is sufficient to account for a much 

 greater variation than is shown for most breeds in Table Y. At the 

 same time the difference in fertility of Shropshire flocks kept in 

 Staffordshire, as compared with other flocks of the same breed kept 

 elsewhere, and of Lincoln flocks kept in Yorkshire, as compared with 

 those kept in the home county, is very remarkable. They certainly 

 suggest that Yorkshire is a more satisfactory habitat for the Lincoln 

 breed than is the home county, and although it is quite possible the 

 method of farming and other influences, in Lincolnshire, are responsible 

 for some of the difference, they can hardly be responsible for all of it. 

 I do not believe that the high percentage of loss in the Lincolnshire 

 wold flocks is due altogether to mismanagement, but if 50 per cent, of 

 the difference between the losses of the wold flocks and the Yorkshire 

 flocks was added to the percentage of twins of the former, there would 

 still be a difference of 17 per cent, of twins in favour of the Yorkshire 

 * See " Percentage of Twins." 



