One man undertook to change that, Alexis Carrel, a student in Lyons who was appalled by Carnot's death, in his hometown, while a number of physicians stood by and watched.

But consider the problem — repairing a tiny, elastic, living tube, part of a network of tubes of different sizes and functions, so that it would retain its ability to channel many gallons of blood every day, birth to death, without a hitch.

The story is that Carrel — Dr. Carrel by 1900 — studied with Marie-Anne Leroudier, one of the most proficient needlewomen in Lyons (her work was exhibited at the Columbian Exposition in Chicago in 1893), learning to make minute, uniform stitches. He developed a triangular system that allowed him to rapidly close up a vein or artery end-to-end without having the stitches adhere to the opposite wall, ushering in the birth of vascular surgery.

Carrel came to the University of Chicago in 1904, where his prodigious 21 months' work as an assistant to G. N. Stewart at the Hull Laboratory laid the groundwork for transplantation surgery. That work was the basis for Carrel's becoming the first scientist working in the United States to win the Nobel Prize for medicine, in 1912. Carrel soon moved on to the Rockefeller Institute for Medical Research in New York.

(Carrel's collaborator at the U. of C., Charles Claude Guthrie, was miffed that he was not included in the Nobel Prize. Guthrie possibly lost points with the Nobel committee for his subsequent experiments in St. Louis with head transplants.)

Carrel was a complicated man, compassion and curiosity mixed up with arrogance and resentment. He was a eugenicist — that is, he subscribed to the false science of "perfecting" the human race by eliminating traits judged to be inferior — and he was also an enthusiastic believer in the miracle cures at the shrine at Lourdes. At the time of his death in 1944, in Paris, he was working on a project for the collaborationist Vichy government.

But after Simon, the fourth of nine children, nearly died of typhoid fever at the age of 16, he found his passion — infectious diseases.

Simon Flexner

Flexner went to work as an apprentice in his brother Jacob's pharmacy, where he learned to use a microscope. Doctors he knew from the store gave him tissue samples for his self-directed studies in histology, the study of microscopic structures in tissues, and pathology.

At 26, he earned his medical degree from the two-year program at the University of Louisville. His younger brother Abraham, a recent graduate of  Johns Hopkins University, arranged for Simon to study pathology there under William Henry Welch, who was helping to bring the scientific method to American medicine.

Flexner became a microbe hunter extraordinaire, helping to suss out the causes of meningitis among Maryland coal miners, bubonic plague in San Francisco's Chinatown, and a common dysentery that is now known as Flexner's bacillus. He also played a critical role in the conquest of polio.

In 1902, Flexner became the head of the new Rockefeller Institute for Medical Research, and this is where the birth story intersects his own. Flexner assembled an amazing team of scientists that included Alexis Carrel, Peyton Rous and Karl Langsteiner who, among other achievements, brought blood transfusion to reality.