Microbial Structures and Staining Reactions 93 



have faced this problem and have arrived at definite answers con- 

 firmed by other workers applying similar or different technics. It 

 is true that when you compare a mouse to an elephant, the mouse 

 really isn't very big. But to an inquisitive bacterial cell, a mouse is 

 a monstrous thing, while a virus undoubtedly looks extremely tiny 

 to this same bacterial cell. Everything is relative. 



Bearing in mind that weight depends upon size and density, 

 it has been calculated that it would take five billion bacteria to 

 weigh one milligram. To express this in another way, a single 

 organism weighs about 0.000,000,000,000,2 gram. A moderate 

 sized drop of milk can easily harbor a number of bacteria ex- 

 ceeding the entire human population of New York City, and there 

 would still be plenty of room to spare in that drop of milk. A 

 farmer, when informed that the milk he had shipped to the 

 creamery a few days previously had a bacterial count exceeding 

 one million, struck his forehead in amazement and remarked, "I 

 wonder how I ever managed to get the lid on the can!" His 

 surprise would have been still greater had he been told that every 

 twenty drops of milk in that forty quart can contained over a 

 million bacteria. It is true that bacteria don't weigh much, nor do 

 they occupy much space, if we are thinking purely in terms of 

 macroscopic rather than of microscopic objects. 



COLLOIDAL NATURE OF PROTOPLASM 



Protoplasm (Greek protos, meaning first, and plasma, meaning 

 formed substance) is the basis of all life, and it is still a biological 

 mystery. Even though scientists have compounded materials ap- 

 parently identical with protoplasm, the synthetic material lacks the 

 spark of life. Hugo von Mohl in 1846 originated the word 

 protoplasm to describe that colorless or gray, translucent, semi- 

 fluid, colloidal substance found in all cells. As our knowledge 

 of cells increased, other words were introduced to describe definite 

 structures within the protoplasm. The term nucleoplasm (some- 

 times called karyoplasm) was applied to the material within the 

 nucleus, and cytoplasai for the material surrounding the nucleus. 

 Protoplasm has certain characteristics in general, but specific 



