Treatment of Grass Land for Elimination of Disease. 8!) 



measures for the destruction of these creatures. Arsenic 

 applied to the skin of infested cattle, burning of tufts of 

 coarse grass, &e., which afford suitable breeding ground for 

 ticks are often suggested for this purpose, but, though con- 

 siderable reduction of their numbers may be effected, the 

 annihilation of the species by such means is not easily 

 accomplished. It is believed that residence on cattle or 

 equines is essential to the life of these ticks, so that keeping 

 grass land free from these animals for a year, or less, would 

 probably mean death to ticks from starvation and freedom 

 of the animals grazing on the pasture from Red-water. 



Of other forms of pollution to which grass land is subject 

 foot-rot of sheep affords a very familiar example. The precise 

 nature of the agent which brings about the pathological 

 changes in the horn of the hoof is, perhaps, not determined, 

 indeed, it may be that organisms of more than one variety are 

 responsible for these changes, and the almost ubiquitous 

 appearance of the disease certainly suggests that the causal 

 factor is widely distributed on our grass lands. Experience 

 of the conditions under which large numbers of sheep in a 

 flock become affected with this troublesome complaint indicates 

 that these are such as tend to soften the horn and prevent that 

 wearing of the ground surface of the wall which keeps the 

 hoof in proper proportion. The vulnerability of the horn and 

 its over-growth thus established are probably more important 

 considerations than that of the micro-organisms which actually 

 invade and disorganise the horn and expose the underlying 

 sensitive structures of the foot to painful impressions. As 

 grass and grass land is wet and soft sheep grazing on it are 

 liable to become the subjects of this disease. In most cases 

 these circumstances cannot be altered, and the most that can 

 be done to cope with them is to select the driest situations 

 available, while this form of contamination is more likely to be 

 counteracted, if not eliminated, by attention to the sheep's feet 

 than to any treatment applied to grass or grass land. 



It is, of course, possible that disease germs may be trans- 

 ported by many and various agencies other than directly by 

 diseased animals, and after gaining grass-land set up in animals 

 there diseases of a more or less enduring nature. An element 

 of risk must always be associated with foreign feeding stuffs, 

 mill sweepings, raw animal manures, road sweepings, &c. 



Though but the fringe of this important subject has been 

 touched on, and that in a fragmentary manner, it is hoped 

 enough has been disclosed to indicate that disease of grazing 

 animals is not an entity which can be eradicated by one 

 universal measure ; that grass land is liable to contamination 

 with the seeds of many diseases for the extirpation of which 



