Five Quarts_ A Personal and Natural History of Blood - Bill Hayes [41]
Its looks were deceiving, however, as Al could find no “wee beasties” swimming in the sample. Drop after drop of smelly water he tried but, alas, nothing surfaced. Yuck, I remember thinking. Is there really water so gross that even bacteria will refuse to move in? He did not look ready to surrender, so I spoke up. “Al,” I said. “Let’s go for blood.”
While he cleaned the slide with his shirtfront, I pulled out my pack of sewing needles, selected a medium-sized one, and poked my index finger. Though I’d pushed hard, no blood appeared. I tried another spot farther down. This triggered a fleeting flashback to high school biology, though it was my lab partner’s blood we studied, not mine—a lucky flip of the coin.
“Ah, there you go,” Al said, nodding, for he’d noticed before I did that both pricks were now bubbles of blood. “More than we’ll need.
“Okay,” he coached, “now get some of it on the end of the needle. Not much, just a bit.” I handed the dipped needle to Al, who smeared the blood on the slide and gingerly lifted the microscope to his eye.
In one of his very first letters to the Royal Society, dated April 7, 1674, Leeuwenhoek noted, “I cannot neglect this opportunity to tell you that I have endeavored to see and know, what parts the blood consists of; and at length I have observed, taking some blood out of my own hand, that it consists of small round globules driven through a crystalline humidity of water.” (By “water,” he was referring to what is now called plasma, the pale liquid in which blood cells are suspended.) Writing again two months later, Leeuwenhoek elaborated, not only describing “the red globules of the blood” but also measuring them. This was standard practice for Leeuwenhoek—he fastidiously measured everything he studied—and another of the man’s innovations, making him the founder of the science of micrometry. The impulse to measure seems to have been perfectly natural to him, a numbers whiz, as well as an extension of his years as a cloth merchant and surveyor. In order to measure particles on such a small scale, Leeuwenhoek had to devise new means of comparison, such as using a single hair or a grain of sand. Thus, he reckoned that one red cell was twenty-five thousand times smaller in volume than a fine grain of sand—or about 1⁄3,200th inch in diameter. Modern measurements indicate that he was almost dead on.
Leeuwenhoek returned over and over to studying blood, constantly refining his understanding. He compared human blood to that of different animal species and noted, correctly, that the “globules” are the same size in all red-blooded creatures regardless of total blood volume, whether in a minnow’s thimbleful, say, or a whale’s many gallons. In addition to discovering red cells, Leeuwenhoek described the coagulant properties of blood and made preliminary observations of the colorless corpuscles now known as white cells, or leukocytes. None of which is to suggest that Leeuwenhoek didn’t make errors. Sometimes when you go out on a limb, the branch snaps. For instance, for the remainder of his life, Leeuwenhoek insisted that red blood cells were spherical when, in fact, they’re more like pinched balls of Play-Doh or, if you will, like sunken jelly doughnuts. Further, in attempting to explain where in the body blood cells originate, he theorized that they formed from minute particles of food that were built up then rounded in the steady rush of the bloodstream, like pebbles polished by the tumble of waves.
He never hesitated to share the smallest details of his findings, and at times, in his nearly four hundred letters to the Royal Society, Leeuwenhoek was forthcoming almost