A SCURVY NOTE
The view has got about that the causes of scurvy were well understood by 1910, that Scott's men probably died of it, and that he was guilty of failing to take the risk seriously. All three of these claims are inaccurate.
Scurvy is a horrible way to die. First your gum swell and bleed. Then your skin goes pale and you start to bruise very easily. Your teeth and nails loosen. You are constantly exhausted. Next the stiffness and pain start, often in the back of the legs. Wounds fail to heal. Most disgusting of all, old wounds that you had long forgotten about break open again and give off a dreadful smell as they begin to rot. If you are tough enough to live through this, your teeth and nails actually fall out, along with your hair.
Between about 1600 and 1800, tens of thousands of sailors were sewn into their hammocks and dumped into the sea after dying this way. Scurvy, they said-but nobody knew what 'scurvy' was. Theories about what caused it were plentiful. Too much damp, not enough sunlight, too much work, not enough work, contaminated food, stale food, poisoning, salty food.
The big breakthrough, or what should have been the big breakthrough, came in 1747, when the Scottish physician James Lind introduced into the Royal Navy the idea of supplementing the diet with citrus fruits. Then, in the 1770s, Captain James Cook sailed around the world three times, and had problems with scurvy only when his men failed to follow his dietary orders. (During his second voyage, the Adventure under Tobias Furneaux was plagued with scurvy, and the cook died of it; at the same time, Cook and the Resolution were entirely free of the disease. The difference was that Cook's men were actually eating the two pounds of sauerkraut per man per week that he had taken with him.) Gradually, despite many bureaucratic obstacles over many decades, the Navy diet improved and scurvy deaths among sailors declined.
Yet scurvy nearly killed both Ernest Shackleton, in 1903, and Teddy Evans (who had been man-hauling longer than almost any of Scott's other men) on the Second Returning Party in 1912. It may even have contributed to the deaths of Taff Evans and Titus Oates, whose injuries would not heal, and conceivably it also hastened the deaths of Wilson, Bowers and Scott (though there is no direct evidence for this, and there is good reason to doubt it). What was going on?
We know the truth now, of course: scurvy is a simple deficiency disease. If your diet contains enough ascorbic acid (vitamin C), you don't get scurvy. If your diet contains none, you remain healthy for at most three to six months and then succumb. Most animals manufacture their own ascorbic acid: we even know the specific gene that does the work. Unfortunately, in the remote ancestry of humans - over 40 million years ago - this gene became a non-functioning 'pseudogene'. Humans, like all primates and some of our more distant relatives, have to get their vitamin C from food.
This specific knowledge came much too late for Scott and his men. In Scott's lifetime, despite Cook's successes, a now largely forgotten debate still raged. Scott got his opinions on the disease from three people: his mentor Sir Clements Markham, his surgeon on the Discovery expedition, Reginald Koettlitz, and his surgeon on the Terra Nova, Edward Atkinson. Like many other medical men at the turn of the century, all three had turned decisively away from the idea that citrus juices were a cure-all. In the late nineteenth century, after the disease seemed fully controlled, several puzzling cases were recorded in which ships without lime juice did better against the disease than ships with it, and the 'juice theory' went into a steep decline. Markham and Koettlitz, in particular, violently denounced it as nonsense.
Like them (and also, it's worth noting, the great Norwegian explorer Nansen), Atkinson favored a competing theory associated with the bacteriologist Sir Almroth Wright. Wright believed that scurvy was associated with increased acidity of the blood and was therefore probably a form of 'ptomaine poisoning'- chemical poisoning caused by the bacteria in (for example) tainted tinned foods. (The literature of the time sometimes refers to the condition as 'scurvy taint,' suggesting the assumption that it was a form of poisoning.) Wright actually thought citrus juices, because acidic, might make the condition worse once it had been contracted. 
Far from ignoring the threat of scurvy on Scott's expedition, Atkinson continually monitored the men's blood acidity, as per Wright's theory. But he was not narrow-minded about what theory to believe. He knew perfectly well that fresh fruits and vegetables, and also fresh meat, sometimes helped prevent the disease; this had been understood for centuries, arguably for millennia. And he clearly recognized that scurvy was a potential threat to the Polar party, for when he brought Teddy Evans in, with what he described as 'a hellish go of scurvy,' he immediately suggested to Silas Wright that the team going south to meet Scott take "apples, oranges and onions".  (All three had been brought down by the returning Terra Nova.) But it wasn't clear in 1910-12 how much value these foods had as a cure (because of a special substance they contained), as opposed to being useful as a preventative (because of contaminants they lacked). The real route to prevention, Atkinson believed, was a diet of fresh and therefore uncontaminated food - an idea reflected in Scott's comments.  Atkinson thought citrus juices were useful, if at all, only because their acidity killed off the bacteria (or neutralized the other poisons) that probably caused the disease. Nevertheless lime juice was part of the daily ration at Cape Evans.
On the evening of Thursday, 17 August 1911, just after the Cape Crozier party returned, Atkinson gave a lecture on scurvy. After hearing him, Frank Debenham wrote in his diary: "Though the incidence of scurvy in the Navy has decreased since lime juice was made a ration, it is the general opinion that lime juice by itself is not a preventative." And Scott wrote, the day after the lecture: "Scurvy seems to be far away from us this time; yet after our Discovery experience, one feels that no trouble can be too great or no precaution too small to be adopted to keep it at bay. Therefore such an evening as last was well spent. It is certain we shall not have the disease here [at Cape Evans], but one cannot foresee equally certain avoidance in the southern journey to come. All one can do is to take every possible precaution."
Ironically, "vital amines" were first proposed as a special class of chemicals just months after the Terra Nova left England. For obvious reasons nobody at Cape Evans was in touch with this latest research, and in any case it was not until 1932 that the Hungarian chemist Albert Szent-Gyorgi earned a Nobel Prize by isolating what he called 'hexuronic acid' and showing conclusively that it was the key to the disease. 
Scott and his men could not have known the real reasons why the value of citrus juice had come under doubt again in the Navy, but Debenham's comment reflects a common and (to many sailors) fatal conflation of limes with lemons. The incidence of scurvy did indeed decrease when the juice of Mediterranean lemons became a standard ration, but a later switch to the more readily available West Indian limes, of 'limey' fame, actually reduced the amount of vitamin C in a Navy ration, already barely adequate, by two thirds. In addition, to preserve the juice in large quantities, and make it more convenient for long voyages, suppliers were concentrating it. They did so by boiling it, sometimes in copper containers; both the heating and the copper helped destroy the ascorbic acid. The result was a juice that kept very well and had no 'antiscorbutic' value at all.
Scott's Polar Party ate both tinned beef pemmican and some fresh pony meat. Unfortunately, even fresh meat is at best a modest source of vitamin C, and drying and cooking tends to destroy what little there is. If they were suffering from the onset of scurvy in March 1912, a supply of frozen seal liver (a favourite treat at camp and very high in vitamin C) might have made a significant difference to their chance of survival. But the balance of probabilities is that they did not yet have symptoms: Wilson never mentioned them, and Atkinson, also a doctor and closely familiar with the disease, examined the bodies in the tent and found none. In any case they probably had no particular reason to take this precaution. They knew that ordinary seal meat was useful against scurvy: an outbreak in September 1902 had led to an immediate shift from tinned food to fresh seal, with encouraging results. But presumably they thought it too likely to spoil on the sledges, or just too cumbersome to carry, especially since they expected to eat some pony meat anyway. What killed them was exhaustion, hunger and cold.
1 Since Almroth Wright was utterly wrong about scurvy and citric acid, it may be worth pausing to remember that on another front he saved tens of thousands of lives. He was responsible both for developing a vaccine against typhoid and for winning an uphill battle to make sure that it was supplied to British troops during the First World War.
2 Atkinson's hastily scribbled note survives. The first two items in it are underlined twice; the word 'onions' is underlined nine times.
3 Nansen actually believed that, faced with the choice between slightly spoiled tinned food and very spoiled tinned food, you should choose the latter. His reason was that the fermentation in the very spoiled food would have killed some of the 'scorbutic' bacteria.
4 In later years, even members of the scientific party added unwittingly to the myth that the scurvy-vitamin connection was clear in 1910. Silas Wright recalled: "I think maybe we all suffered too from a general deficiency of the many vitamins which are now known to exist, but which had not been discovered in 1910, except of course the antiscorbutic vitamin." (Emphasis added.) Wright's memory was playing tricks on him: once again, 'the antiscorbutic vitamin' was not discovered until a full generation later.