one time thought to be only the products of living tissues—camphor, for instance, and some of the alkaloids used in medicine. But what is the difference between our process and that of Nature? What happens is this. The substance produced by synthesis always appears in what is called a racemic form. It consists of two sets of substances—one set having its asymmetry right-handed and the other left-handed, so that the product as a whole behaves like an inorganic, symmetric compound; that is, its two asymmetrics cancel one another out, and the product is optically inactive and has no power to rotate the beam of polarised light. To get a substance exactly equivalent to the natural product, we have to split it into its two asymmetric forms. We can’t do that mechanically. We can do it by the exercise of our living intelligence, of course, by laboriously picking out the crystals. Or we can do it by swallowing the substance, when our bodies will absorb and digest the dextro-rotating form of, for example, glucose, and pass the laevo-rotating form out unchanged. Or we can get a living fungus to do it for us, such as blue mould, which will feed on and destroy the dextro-rotatory half of the racemic form of paratartaric acid and leave unchanged the laevo-rotatory half, which is the artificial, laboratory-made half. But we can’t, by one mechanical laboratory process, turn an inorganic, inactive, symmetric compound into one single, asymmetric, optically active compound—and that is what living matter will do cheerfully, day by day.”
Waters finished his exposition with a smart little thump of the fist on the table. I knew what that was. It was the postman’s knock, bringing the answer to that letter of mine. A horrid sinking feeling at the solar plexus warned me that in a very few minutes I should have to ask a question. Why need I do it? The subject was remote and difficult. I could easily pretend not to understand. If there really was a difference between the synthetic and the natural product, it was not my business to investigate it. Waters was changing the subject. He had gone back to the first day of creation. Hang him! Let him stay there!