Surprisingly to me, for an educated man of his time, Dana gives no indication of knowing the cause of scurvy. He mentioned it a couple times before, with no sign of understanding it at all. Here he is describing crew of a Russian vessel he visited in San Francisco harbor:
"To a Russian, grease is the greatest luxury. They looked with greedy eyes upon the tallow-bags as they were taken into the vessel, and, no doubt, would have eaten one up whole, had not the officer kept watch over it. The grease seemed actually coming through their pores, and out in their hair, and on their faces. It seems as if it were this saturation which makes them stand cold and rain so well. If they were to go into a warm climate, they would all die of the scurvy."
He had mentioned "grease" comprising too much of their diet, but show no comprehension of value of fruits and vegetables.

Could it be a joke along the lines that normal people get scurvy if deprived of fruit and veg., but Russians get it if deprived of grease?

Bingley

doesnt meat, (along with foods like potatoes) provide some vit. C? could it be the grease is an unhealthy sourse of vitimins?
(i remember reading something about meat being a surprizing sourse of vit. C, when reading about the Atkin's diet.)

Scury existed because foods rich in vit. C were expensive (oranges or meat) or boring/gassy/socially unacceptable (cabbage). The english navy got sailer to take their lime juice by lacing it with rum.

Quite a while ago, we had a thread about scurvy.
In 1739 Lord Anson circumnavigated the globe. A thousand sailors died of scurvy. Wow posted having read that officers didn't get scurvy because they could
afford orange marmelade, which was too expensive to give the crew. The officers believed that poor hygiene was cause of death of the sailors. In 1754 Lind published his Treatise on scurvy.
But only after forty more years did the Admiralty compel
giving sailors lemon juice.
If Dana was making a joke about scurvy being caused by poor hygiene, it was a very bad joke. He doesn't mention what kept him from getting scurvy. I don't remember any metion of fruit except "plum duff". And I don't remember any mention of vegetables. They did get fruit at Juan Fernandes. Elsewhere I have read that it could take six months on a deficient diet for symptoms to appear.