With these facts in mind, we can hardly fail to be amused whenever certain simple chemical reactions obtained _in vitro_ are hailed as “clue to the origin of life.” When it was found, for instance, that, under certain conditions, an aldehyde (probably formaldehyde) is formed in a colloidal solution of chlorophyll in water, if exposed to sunlight, the discovery gave rise to Bach’s formaldehyde-hypothesis; for Alexis Bach saw in this reaction “a first step in the origin of life.” As formaldehyde readily undergoes aldol condensation into a syrupy fluid called formose, when a dilute aqueous solution of formaldehyde is saturated with calcium hydroxide and allowed to stand for several days, there was no difficulty in conceiving the transition from formaldehyde to the carbohydrates; for formose is a mixture containing several hexose sugars, and Fischer has succeeded in isolating therefrom acrose, a simple sugar having the same formula as glucose, namely: C₆H₁₂O₆. Glyceraldehyde undergoes a similar condensation. In view of these facts, carbohydrate-production in green plants was interpreted as a photosynthesis of these substances from water and carbon dioxide, with chlorophyll acting a sensitizer to absorb the radiant energy necessary for the reaction. The first step in the process was thought to be a reduction of carbonic acid to formic acid and then to formaldehyde, the latter being at once condensed into glucose, which in turn was supposed to be dehydrated and polymerized into starch. From the carbohydrates thus formed and the nitrates of the soil the plant could then synthesize proteins, while oxidation of the carbohydrates into fatty acids would lead to the formation of fats. Hence Bach regarded the formation of formaldehyde in the presence of water, carbon dioxide, chlorophyll, and sunlight as the “first step in the production of life.” Bateson, however, does not find the suggestion a very helpful one, and evaluates it at its true worth in the following contemptuous aside: “We should be greatly helped,” he says, “by some indication as to whether the origin of life has been single or multiple.” Modern opinion is, perhaps, inclined to the multiple theory, but we have no real evidence. Indeed, the problem still stands outside the range of scientific investigation, and when we hear the spontaneous formation of formaldehyde mentioned as a possible first step in the origin of life, we think of Harry Lauder in the character of a Glasgow schoolboy pulling out his treasures from his pocket—“That’s a wassher—for makkin’ motor cars.” (“Presidential Address,” cf. Smithson. Inst. Rpt. for 1915, p. 375.)