88 Treatment of Grass Land for Elimination of Disease. 



disease has advanced to the stage at which its germs were being 

 discharged in profusion. Quite recently the preparation of a 

 specific diagnostic vaccine has been announced by Messrs. 

 Twort, M.R.C.S., and Ingram, M.R.C.V.S., of the Brown 

 Institution, London, for which is claimed the power to 

 diagnose the disease in its early stages. If this, or any like 

 means, should prove effectual and practicable in the field 

 there will be at our disposal a highly valuable form of 

 treatment for averting pollution of grass land, and so of 

 eliminating this serious malady to which our more numerous 

 grazing animals are liable. 



Contagious abortion of cows is probably sometimes con- 

 tracted on pasture as a result of its contamination by the 

 abortion, discharges from the womb, &c. It is now known 

 that infection may take place by ingesting the germs of the 

 disease, and, while attention must be paid to disinfection of 

 the foetus and any discharge which may be discovered, the 

 elimination of this malady from grass land is surelj^ effected 

 by excluding female bovines, its only subjects, for lengthened 

 periods. 



Recent reports as to the danger from discharge of tubercle 

 bacilli in the ffeces of tuberculous cattle would naturally 

 suggest tuberculosis as being another serious form of con- 

 tamination of grass land, but, though it may not be denied 

 that it is possible for healthy animals to contract the disease 

 on pasture, many circumstances indicate that such is not by 

 any means the ordinary situation in which the germs of this 

 affection are acquired. Sheep which so frequently graze with 

 and after cattle, though quite susceptible, are extremely rarely 

 affected, a remark which largely applies to grazing cattle, 

 which have never been housed. 



As suggestive of the variety of the measures to be adopted 

 for the elimination of disease from grass land, reference 

 may be made to the affection of cattle known as Red-water, 

 which occurs pei'sistently on certain pastures, usually, though 

 by no means exclusively, of rather inferior quality. Until 

 recently this disease was attributed to defective nutritive 

 quality of herbage, but revelation of its ti'ue nature shows it 

 to be caused by micro-parasites (piroplasms) introduced through 

 the skin into the blood by ticks which contaminate the grass 

 land in which the disease is contracted. For our purpose it is 

 highly important to recognise the fact that the disease producing 

 piroplasms which the tick inoculates have been derived from 

 the blood of infected animals. It is taken that ticks are 

 essential to the ])roduction of this disease, and. that if no 

 ticks were available there would be no Red-water. To 

 purify the pasture it is desirable to adopt all i)racticable 



