FIKLD NATURALISTS' CLUE 201 



appear to be grave reasons for assuming that the disease is 

 connected with the presence of ticks upon the animal-;. "Where 

 "louping-ill is found there the ticks are always present: where 

 ticks do ii"' exisl there is no disease ; the sheep are attacked at 



season when the ticks appear after their winter's rest : and, 

 lastly, treating the pasture for the destruction of ticks not only 

 gets rid of ti but is found to stamp out "louping-ill. " 



These general deduc in to place the matter in a very clear 



light ; the weakest part of the evidence is the vague character of 

 the scientific demonstration of the manner in which the ticks are 

 connected with the disease. 



But this latter charge cannot be brought against the work 

 of the United .States Bureau of Animal Industry, dealing with 

 the suspected connection between the great cattle tick of the 

 Southern States and the "Texan cattle fever." 



The report of that Department for the year 1891-2 leaves 

 no doubt about this connection. There is, namely, present in the 

 blood of the cattle suffering from disease an infusorian which 

 quickly destroys the red blood corpuscles. This minute organism 

 has also been detected in the body of the tick. It has been 

 again and again transmitted from diseased animals to healthy 

 ones by means of the tick and tick alone. The presence of this 

 infusorian in the blood is regarded as diagnostic of the disease f 

 and the effect of its corpuscle-destroying powers is seen all over 

 the bod}- as well as in the red-coloured urine, which has won for 

 the disease the Colonial name of "red-water." 



Here then, undoubtedly, the tick is bhe bearer of a deadly 

 disease. And it is worth while remembering that nowhere else 

 has the question of the action of the ticks upon cattle been 

 thus fully and faithfully worked out. There is no reason why 

 the Southern States should be singled out for this particular 

 display of the hidden relations between parasite and host. 

 Already much attention is being devoted to the Cape ticks where 

 red-water is prevalent. It is quite possible that some of the 



ire cattle i in other parts of the world are caused bv 



ticks, and that other countries will, in their turn, be forced to 

 face this problem. 



It is a matter of common experience that it is the poor cattle 

 of the flock which are covered with ticks. The strong and sleek 

 members will have ticks but usually scattered or isolated ones: 

 it is the weak one of the herd which sickens us with its covering 

 of ugly parasites. 



This fact has been explained in. various ways. It has been 

 asserted that the weak animals are unable to rub off and get rid 

 of the tick s by forcible means, but! can hardly think that this is 

 a correct explanation. The insertion of the proboscis of the 

 tick is said by travellers to be painless, and the gradual pumping 



