INTRODUCTION. iii 



horse, ox, and pig in domestication, they live their whole lives 

 on the land, and are uninterruptedly dispensing such internal 

 and external parasites, and some one or other of germs of specific 

 diseases as may attack them, on to the land. Therefore the land 

 becomes so infested with them that other sheep following them 

 can scarcely fail to contract the same ailments from which they 

 suffered. That is a common experience in over-populating, whether 

 it be with man or any of the lower animals. It is only by keeping 

 fewer animals, and resting the land for longer periods, so that 

 the parasite or germ may be starved out, or by following such 

 controlling methods as experience or science has pointed out 

 as effecting disease eradication, that reasonable hope can be enter- 

 tained of keeping the sheep in health. Successful shepherding 

 depends very much on the thoroughness with which diseases and 

 ailments are kept in check. 



Without being able to ascribe a specific reason for their actions, 

 farmers and shepherds have recognised that land becomes unhealthy 

 if overstocked, and that conditions indicate that they must rest 

 the land. They were not to blame, because, until the man with 

 the microscope came along and saw what no man could see with 

 the naked eye, they were forced to remain in ignorance of 

 certain diseases. No one knew they were there, consequently 

 no one could tell how or when they were contracted. No wonder, 

 then, that when sheep ailed, and for no particularly apparent cause 

 scoured, withered and died, in spite of all that sheep-lore could 

 suggest, sheep were regarded as being delicate. Moreover, 

 it is ever the shepherd's duty to try to discover the cause of ailing, 

 and to supply the remedy, and to his credit it can be said that, 

 where the cause is not deeply submerged, he very frequently arrives 

 at the right conclusion. But when the cause is due to something 

 that no man has divined, he is bound to be at a loss to attack 

 it in the right place. Following his usual and right practice, he 

 has to look for something more obvious, and when one knows 

 that these until recently hidden diseases existed, his " shots " 

 at the cause seem to be ridiculous. As a matter of fact, they show 

 only the more conclusively how necessary it is that all encourage- 

 ment should be given to those who systematically endeavour to 

 trace out the nature, origin, and prevention of the diseases which 

 affect sheep. 



Not many years ago a prejudice existed against the use of arti- 

 ficial manures, because it was held that they produced unhealthy 

 food for sheep the sheep went wrong when consuming crops 

 manured with them. It is very easy to understand how shepherds 

 with flocks troubled by a mysterious disease should jump to the 

 conclusion that it was due to something immediately influencing 

 them ; no other cause presenting itself, what more obvious than 



B 2 



