4 
The Colorado Experiment Station. 
in the mysteries of speculation and conjecture for nearly two hun¬ 
dred years, until finally in 1882, Dr. Robert Koch, a German bac¬ 
teriologist, discovered a means of growing bacteria outside of their 
natural environment. While great progress has been made in the 
science of bacteriology since that time, and numerous new and 
highly specialized methods of cultivating germs have been devised, 
yet it is interesting to note, in passing, that many of these depend 
upon the fundamental principles demonstrated by Koch, and with¬ 
out his splendid achievements, they might never have been possible. 
The public has been extremely unfortunate in the way in which 
it has acquired a great deal of its knowledge of bacteria. Much of 
this information has come to us through the medium of patent 
medicine advertisements, quack medical advice, and testimonials 
for worthless water filters. What one of my readers, while con¬ 
sulting the family almanac to find the time of the next new moon, 
has not paused for a moment to look at some hideous picture, pur¬ 
porting to be the exact likeness of the germs of some terrible dis¬ 
ease, which can be cured absolutely by taking two bottles of So 
and So’s Bitters? Our conception of bacteria as gained from this 
sort of rubbish is as far from the truth as the east is from the west. 
Everything from an innocent cray fish to a writhing sea serpent 
with yawning jaws, gnashing teeth and a lashing tail is herded into 
these illustrations to send a thrill of horror over the victim who 
reads his fate. 
Bacteria are very simple in shape, and can be divided on this 
basis into three general classes. An easy way to remember the 
three different groups is to think of them as resembling in outline 
lead pencils, marbles and cork screws, although, of course, so small 
as to be seen only by the aid of a powerful magnifying glass. (See 
Plate I.) The bacteriologist knows the lead pencil or rod type 
as a bacillus, the marble or spherical one as a coccus, and the cork 
screw, curved or comma form as a spirillum. The bacillus group 
has the largest membership of the three, and includes such germs 
as produce typhoid fever, diphtheria, tuberculosis, anthrax, lock 
jaw, pear blight, alfalfa bligfit, potato wilt, black rot of cabbage, 
bitter milk, sauer kraut, vinegar, etc.; next in numbers come the 
cocci (pronounced coxi), represented by the germs of pneumonia, 
sore throat, erysipelas, boils and pus; the spirilla constitute the 
smallest division, in which we find the germs of Asiatic cholera, 
syphilis and relapsing fever. These are only a few of the hundreds 
that are known, but they will serve to illustrate the classification. 
Next, let us see something about the size of these tiny plants. 
