156 WOOLFOLK : 



having once taken a stain, it fixes it very firmly, being called 

 an acid-fast bacteria. Mineral acids will not discolor it like 

 most other bacteria or animal substances, hence the absolute 

 surety of distinguishing it when prepared rightly by the 

 microscopist. 



The tubercle bacillus grows within a wide range of tempera- 

 ture; the human bacillus in temperature limits of 85° to 104° F.; 

 bovine bacilli in practically the same temperature; the bacillus 

 from birds, 75° to 114° F., and in cold blooded animals, such 

 as turtles, they multiply at a temperature anywhere from the 

 freezing point up to 110° F. It appears that the tubercle 

 bacillus is one which is able to adapt itself to a wide range of 

 temperature, and is believed now to be one and the same 

 organism wherever found, but modified somewhat by condi- 

 tions of environment. 



In form it appears under the microscope in the shape of little 

 rods, whose length is usually four or five times its diameter, 

 and measuring from two to four microns — a micron being 

 1-25,000 of an inch. So, if it is possible for you to imagine 

 anything rod shaped so small as i - 1 2 ,000 to i -6000 of an inch in 

 length, you have an idea of the tubercle producing organism. 



The name tuberculosis comes simply from the form or 

 microscopical appearance of the disease, it appearing usually 

 in shape of little tubers or elevations upon the surface of the 

 part affected. 



The difference between the microscopic appearance of 

 human and bovine tubercle bacilli is very slight. (I use the 

 bovine bacillus in making comparison, as that is now con- 

 ceded to be the one from which all other animal tuberculosis 

 emanates). The bovine variety usually is shorter, thicker 

 and without a beaded appearance, while the human variety is 

 usually longer, more pointed and showing a beaded appear- 

 ance. Yet, exhaustive experiments as to morphology or form 

 of the tubercle bacillus have failed to establish any reliable or 

 constant difference. It has been found that no character is 

 possessed by one in one host, but what may be produced in 



