Leeuwenhoek’s 
Announcement. 
Theory 
of 
Plenciz. 
BACTERIOLOGY IN A NUTSHELL. 
were these objects that millions of them were 
found to exist in a single drop. 
The researches of Leeuwenhoek were contin¬ 
ued and in 1683 the world received another an¬ 
nouncement—the discovery under the compound 
microscope of a special form of bacteria in the 
scrapings of teeth and in saliva. This scientist 
presented the results of his work of research to 
the * Royal Society of London, England; suitable 
engravings accompanied the gift. We are not 
told whether or not Leeuwenhoek in any way 
connected the germs he discovered with disease 
causation; the supposition of authorities is that 
he did not. 
No attempt was made to classify, separate or 
identify the germs discovered by Leeuwenhoek, 
although many noted scientists of that century 
believed them, to be the cause of certain changes 
in the tissues of the human structure. It was not 
until the year 1762 that Antonius Plenciz, a phy¬ 
sician of Vienna, began ascribing to the micro¬ 
organisms discovered by Leeuwenhoek the power 
to produce the so-called infectious diseases. 
The theories advanced by Plenciz were these: 
I . —That the material which caused the infec¬ 
tion was a living substance; 
II. —That this living substance multiplied with¬ 
in the system, and that it could be thrown off by 
individuals and carried by the air to others; 
III. —That each separate infectious disease was 
brought into existence by a special germ which 
could cause no other disease; contending, in order 
to uphold his belief, that as only one kind of 
*Leeuwenhoek was chosen Fellow of the Royal So¬ 
ciety of London in 1685. 
IQ 
