258 QUEENSLAND AGRICULTURAL JouRNAL. [1 Sept., 1897, 
Tick Fever. 
By ©. J. POUND. 
Ty the accompanying photo-micrograph of blood from a bullock suffering from 
acute tick fever, showing intra and extra cellular organisms, some of the latter, 
it will be noticed, are quite round, while others are pear-shaped, the latter 
being quite characteristic. In the acute stage of the disease, these organisms _ 
are found more frequently in pairs inside the red blood corpuscles. 
In the early stages of the disease, and when an animal has recovered, they 
are found as a rule existing singly outside the blood-cells, moving free in the 
serum. In this stage they are actively motile, and invariably possess a 
delicate filamentous tail known as a flagellum, by means of which the organism 
propels itself through the serum amongst the blood-cells. A further use of 
the flagellum is to enable the organism to penetrate the red blood-cell. As no 
method has been discovered by means of which the flagellum can be stained, 
and from the fact that they cannot be photographed in the living condition, 
only the accompanying drawing can be given, but it may be mentioned that 
this is a faithful drawing from a specimen of blood examined under the most 
perfect form of apochromatic, one-twelfth oil immersion lens, illuminated by 
means of a specially devised paraffin lamp. ‘The specific name given to this 
organism is Pyrosoma Bigenimum. 
The magnification is exactly 500 diameters. The photo-micrograph was 
taken by Dr. John Thomson, of Wickham terrace, Brisbane, from a specimen 
stained with Kuhne’s methylene blue, and prepared by Mr. C. J. Pound. It 
may be worthy of mention that this is the first photo-micrograph ever taken of 
this particular micro-parasite. 
