H. G. Wells 
The Stolen Bacillus 

‚This again, ‚ said the Bacteriologist, slipping a glass slide under the microscope, ‚is a preparation of the celebrated Bacillus of cholera-the cholera germ.‘
The pale-faced man peered down the microscope. He was evidently not accustomed to that kind of thing, and held a limp white hand over his disengaged eye. ‚I see very little, ‚ he said.
‚Touch this screw, ‚ said the Bacteriologist; ‚perhaps the microscope is out of focus for you. Eyes vary so much. Just the fraction of a turn this way or that.‘
‚Ah! now I see, ‚ said the visitor. ‚Not so very much to see after all. Little streaks and shreds of pink. And yet those little particles, those mere atomies, might multiply and devastate a city! Wonderful!‘