76 Treatment of Grass f, and for KUmination of IHsease. 



poisonous plants, or toxic matters, such as lead, arsenic, &c., 

 which are occasionally met with on grass land, nor such as 

 depend on its abundance, succulence, dryness, or other such 

 characters. 



Considerations suggested by the title of this article are 

 many and of wide range, and though there may exist some 

 general principles, consistent wdth good agriculture, which 

 should always be adopted and acted on, the primary and 

 essential condition to be obsei'ved in attempting to eliminate 

 diseases from grass land is the determination of the precise 

 nature of the maladies it is desired to deal with, and it would 

 prove a dangerous fallacy to regard disease as an entity, or 

 to assume the existence of any panacea for the extirpation 

 from grass land of all the diseases to which grazing animals 

 are liable. 



The living organisms, which commonly, though not exclu- 

 sively, render gi-ass land dangerous for stock are parasitic 

 worms and bacteria. With the exception of a small number 

 of the latter, such as those responsible for the i)roduction of 

 black leg and tetanus, which are believed to live in the 

 soil — soil organisms — the disease-producing organisms which 

 contaminate our grass lands are derived from animals and are 

 incapable of maintaining their power to harm live stock or, 

 indeed, their existence for any great length of time apart from 

 animals susceptible to the diseases of which they are respec- 

 tively the causal agents. It is obligatory on the majority of 

 these organisms to spend some portion of their lives in such 

 anini'ils, and if these are not available they perish. The length 

 of the period during which disease germs are capable of 

 maintaining their existence in the outer world, and so of 

 continuing to contaminate pastures, can only be approximately 

 measured. The spores of anthrax under certain conditions 

 retain their vitality and efficiency for periods extending over 

 several years, but this may be taken as the exception rather 

 than the rule, and it will pi'obably be safe to assume that in 

 case of most of the specific diseases to which grazing animals 

 are commonly subject, withdrawal of all live stock for a whole 

 year would result in death of their causal germs and purification 

 of the pasture. 



Further, it is well established that while certain organisms 

 induce disease in all live stock, others atfect only animals of 

 certain species. Advantage of this characteristic may be taken 

 for the elimination of some diseases of the worst form. For 

 instance, the small red bowel-worm, which pollutes many 

 grass lands, and in some does serious harm to horses, affects 

 animals of the equine species only, and residence in the horse 

 or kindred animal being essential to its life, their exclusion 



