30 THE AMERICAN MONTHLY [Jan 



the plate's action and the degree of magnification of the 

 object. Gaudet used a wooden box for a camera. It is of 

 the shape of a four-sided truncated pyramid. The lower 

 opening - slides over the microscope tube and the upper 

 carries a frame of ground glass. He first removes the 

 eye-piece and places the camera on that' part of the tube 

 which holds the objective. The slide is well fixed to the 

 stage and focused as usual but the head of the observer is 

 covered with an opaque cloth. Remember that the image 

 of the object will be reversed but real and magnified. 

 After exposure the plate is developed and the prints made 

 as usual. 



BACTERIOLOGY. 



Tick Fever in Cattle. — C. J. Pound has worked out 

 protective inoculation for Tick Fever. Up to the present 

 time some thousands of head of cattle have been inocula- 

 ted, and the results have proved highly satisfactory, for 

 when such cattle are subjected to gross tick infection, or 

 injected with virulent blood, they remain perfectly im- 

 mune, while the "controls," or unprotected animals, sub- 

 jected to the same conditions, are readily attacked with 

 severe acute fever, which often ends fatally. So success- 

 ful have our experiments been that numbers of stock- 

 owners, whose cattle are threatened with an invasion of 

 tick, have lost no time in systematically inoculating the 

 whole of their herds. He has been kept busy inoculating 

 a number of valuable stud bulls and heifers from Victoria 

 and New South Wales, which are to be sent to North 

 Queensland, where the ticks are very bad. He had some 

 bottles containing several species of ticks (preserved in 

 3 per cent formalin,) with notes on the locality, and the ani- 

 mals native or other, that he had found them ou. In some 

 species he had only kept females, as the males are never 

 seen even by observant bushmen, who are constantly meet- 

 ing with ticks. Every species of tick (other than the gen- 

 uine Cattle Tick, the cause of "Tick Fever" or "Red- 

 water" in cattle) is known to bushmen, squatters, etc., as 



