HISTORIC 13 



hoek's discovery of bacteria these organisms were held 

 to be the cause of a great variety of diseases. In fact, 

 for some time people seemed "bacteria mad." We now 

 know that bacteria are associated only with a certain 

 group of diseases which we call infectious diseases. An 

 infectious disease Is caused by a living germ, though 

 not necessarily by a bacterium.^ For example, typhoid 

 fever, diphtheria, tuberculosis, and pneumonia are caused 

 by bacteria; malaria and syphilis, by tiny germs known 

 as protozoa^ ; w^hile certain diseases of the hair and skin 

 are caused by fungi. ^ The great importance attaching 

 to infectious diseases as a class arises from the fact 

 that they are communicable. Moreover, if the germ of 

 a particular disease is known, the possibility is given of 

 devising means to prevent the spread of the disease, i. e., 

 the transmission of the germ to others. For this reason 

 it is important that nurses should have some knowledge 

 of the nature and characteristics of germs. The study 

 of germs is called bacteriology,- and this usually includes 

 not merely bacteria, but also protozoa, yeasts/ and fungi. 

 The term "microbe," so frequently used by the laity, is 

 synonymous with the term ''germ," and is usually taken 

 to include the several classes of micro-organisms just 

 mentioned. 



^ Bacteria are microscopic, unicellular vegetable organisms that 

 multiply by transverse division. 



2 Protozoa are microscopic, unicellular animal organisms. 



^ Fungi are microscopic, multicellular vegetable organisms. 



* Yeasts are microscopic, unicellular vegetable organisms that 

 multiply by a peculiar process called budding. 



