282 OTHER GERM DISEASES. 
results left no loophole for criticism, proving that this bacterium was 
the cause of anthrax, and thus for the first time demonstrating that 
an infectious disease was produced by a bacterium multiplying 
within the body of the animal in which it grows as a parasite. 
The bacterium in question, Bact. anthracis, is a rod of moderate 
size (Fig. 52). It multiplies by repeated division, the elements re- 
maining attached to form long chains. Sometimes these long 
threads show no signs of the divisions, and in certain media they 
form marvelously twisted and contorted masses. When in an 
active growing condition, this bacterium is readily killed by ordinary 
disinfecting agents and by a moderate heat, a temperature of about 
1 60 F. easily destroying the rods. But it produces resisting spores 
which can easily be distinguished inside the rods as clear, glistening 
bodies. It is their resistance to ordinary agents that makes anthrax 
so persistent, and this high resistance must be borne in mind when 
the attempt is made to disinfect a stable which has been occupied by 
an animal having this disease. These spores will resist the action of 
5 per cent, carbolic acid solution for half an hour, or a i per cent, 
solution of corrosive sublimate for about the same length of time. 
Few other living bodies can resist such treatment. The spores will 
also resist a temperature of about 280 F. for two or three hours. 
When immersed in liquid they are much more easily killed, since the 
temperature of boiling, if maintained for a few minutes, is com- 
monly sufficient to destroy them. When dried the spores may 
remain alive for a long time, many years at least, and yet all the time 
retain their power of developing when placed under proper condi- 
tions. All of these facts evidently make the disinfecting of an 
infested locality a matter of very great difficulty. 
Method of Infection. Although this disease is extremely fatal, 
animals affected rarely recovering, it is not particularly contagious, 
and is rarely communicated directly from animal to animal. One 
common method by which cattle are infected appears to be through 
the food which they crop in the fields. It has often been noticed 
that the disease breaks out in a herd shortly after it has been turned 
out into a new pasture. In some of these cases which have been 
investigated the explanation is simple. In such pastures bodies of 
