1 May, 1899.] QUEENSLAND AGRICULTURAL JOURNAL. 393 
Cape Colony—the Common Blue or Blood Tick. With the object of settling 
this point, at any rate so far as the common species in Cape Colony is con- 
cerned, a careful study has been made of these three forms, and the following 
notes are the results of these comparisons :— 
“Mhe fact that Redwater is carried from beast to beast by the agency of 
ticks was discovered but a few years ago by official investigators in the United 
States of America, where the disease has been the direct cause of great losses 
from time to time. These investigators found that one kind of tick, Rhzpi- 
cephalus annulatus (Say) or as it is more commonly known, Lvodes bovis, was 
the agent which disseminated the disease, and proved that not only did the 
bites of the ticks produce the disease, but further that the disease, or 
power of producing it, was communicated from the maternal tick 
through its eggs to the young. Subsequently when this Redwater 
broke out in Queensland, Australia, it was found associated with a 
tick whieh many of us regarded as identical with the American one, 
and as this tick spread from district to district, so-the disease spread with it. 
In Cape Colony, Redwater has been gradually extending its range from the 
north along the eastern seaboard, and the common blue or blood tick is no 
doubt the chief distributing agent. This species is referred to as the supposed eo 
or chief distributing agent of the disease because of the great possibility that 
it is not the only agent, nor the only tick, for there is a probability that some, 
if not all, of our other common species, such as the larger Blue, the Red, and | 
and the two Bontes, may also act as transmitters; a probability enhanced by 
the fact that these investigations have shown that the Australian, the North 
~ American, and the 1ocal Common Blue, though closely allied and of the same 
genus, are distinct species. But as, up to the present, there does not appear to 
be any conclusive technical evidence upon this important point, I venture to 
draw attention to it as being a question invested with so much interest and 
practical importance, that it is well worthy of attention, particularly in Cape 
Colony, where the opportunities of investigating it are so great. 
“ Another interesting feature is that whilst in Australia and, 1 believe, the 
United States too, the ticks were strangers to those parts to which they carried 
the disease, such is not the case in Cape Colony. Our Blue Vick (Rhipt- 
cephalus decoloratus, Koch) oecurs in many parts of the colony, aud is found 
where, I am given to understand, Redwater has never been known and where 
cattle could not have become immune. That the ticks are actually dissociated 
from the discase in these parts is proved by the fact that imported cattle do not 
contract Redwater when brought into contact with the native éattle. In Australia 
and North America the ticks have never to my knowledge been reported as so 
dissociated from the disease, and fever-stricken cattle were always infested with 
a particular tick, and unless a beast was actually immune by birth or 
had become so by previous infection or inoculation, the bites of these 
ticks were followed by the fever. There are, however, in both countries, 
particularly in the more southern and warmer parts of the United States, parts 
where tick-intested cattle exist in great numbers and do not suffer from acute 
Redwater. These cattle are, however, natives, and inherit their immunity from 
the disease while still cartying in their blood, its ‘germs.’ Erom them the 
ticks are known to take the disease to susceptible cattle either when mixing | 
with these other cattle or grazing over the same ground within a certain 
period after they have crossed it. ‘These susceptible animals have the disease. 
carried to them by the young or larval ticks hatching from the eggs laid by 
those dropping from the former cattle. Ground travelled over by the cattle 
which carry the disease in their blood, remains infected with the disease only 
so long as it is infested with these larve, and this period is limited by the 
length of time that they can live without food. his again, providing there is 
no reinfestation, 1s more or less extended according to climatic conditions,— . 
heat and coid, dryness and dampness; young ticks being very subject to such 
yariations and capable of lying a great while when they are favourable. 
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