894 QUEENSLAND AGRICULTURAL JOURNAL. [1 May, 1899. 
Ground is said to remain infested for as many as six months in winter and two 
in summer in the case of the American Redwater tick, of which it is recorded 
that :—* 
“ (1.) The delay in the beginning of egg-laying is nearly three weeks in 
winter as compared to twenty-four to forty-eight hours in summer.y 
“(2.) The time elapsing between the laying of the first and the last egg 
by a female is, in summer temperature, only a few days, while in winter it may 
extend over a period of five weeks. 
* (3.) In winter incubation is almost suspended, and months may elapse 
before hatching takes place. In summer the normal incubation period is about 
twenty days. 
_“ (4). Seed ticks (larvae) are capable of existing without food four and 
one+half months in winter; in summer the time survived was about two 
months. 
“The short summer period does not, I am told by Mr. Hutcheon, C.VS., 
actually apply to all our local conditions, as there are certain evidences of veldt 
remaining infected for far greater periods.”’ 
*The following information is quoted from Bulletin 51 (2nd Ser,) of the Louisiana State 
University and A. & M. College. The Cattle Tick and Texas Fever, by W. H. Dalrymple, H. 
A. Morgan and W. R. Dodson. BAton Rouge 1898. 
+In the case of the Bonte Poorten Tick (Amblyomma hebreum, Koch) we find that there was 
a delay of from two to three months in beginning egg-laying in winter (May to July), and about. 
a week in summer (January). 
Animal Pathology. 
TUBERCULIN: ITS HISTORY, PREPARATION, AND USE. 
By C. J. POUND, F.R.M.S., 
\ Director of the Queensland Stock Institute. 
[Read before the Royal Society of Queensland, 17th December, 1898. | 
Every day brings forth evidence of the prevalence of tuberculosis among cattle, 
in every country throughout the civilised world, but it is particularly inter. 
esting to note that by far the greater number of cases have only been detected 
_ by means of that most invaluable agent, tuberculin. | 
HISTORY. 
In 1882, Robert Koch, the eminent German Bacteriologist, announced 
that he had discovered a special bacillus in tubercular tissues, which he isolated 
and cultivated artificially in or on specially prepared nutrient media outside 
the animal body; also, that he could reproduce the disease by means of inocu- 
lation with the cultivated bacillus. Subsequent investigation proved that the 
bacillus of human consumption was identical with that which caused tuberen- 
losis in cattle. 
In 1890, Koch made another interesting discovery, viz.:—That the isolated 
poisonous products of the tubercle bacillus were: (1) capable of preventing 
the effects of the inoculation of tuberculous material, (2) of healing in certain 
manifestations of tuberculosis in the early stage, and (8) of indicating the 
resence of tuberculous lesions, when all other methods of diagnosis entirely 
ailed. 
Tuberculin is the name given by Koch to the glycerine extract of the 
poisonous products of the tubercle bacillus. 
Although there are some authentic cases of tuberculosis in the early 
stages in human beings that have completely recovered after treatment, 
generally speaking tuberculin, as a cure, has not come up to expectations, but 
