"Why?" asked Jack.
"Because our stomachs are full. They have been seriously weakened by several days of starvation, and are apt to do their work rather badly for a time. Let's give them a chance."
"But, Doctor," said Jack, "I have noticed that all the animals lie down and sleep as soon as they have fed heartily. Why isn't it a good thing for men to do the same thing? Men are after all, animals on one side of their nature."
"Yes, I know," said the Doctor, "and I have known physicians to argue in that way in favor of late suppers. But experience hardly bears out the argument. A man may sleep well on a heavy meal, but often he gets up with a bad taste in his mouth and with a morbid craving for food, which means that he hasn't properly assimilated the food that he has already eaten."
"What do you mean by 'assimilating' food?" asked Tom, adding: "I'm afraid you'll think me very ignorant."
"Not at all," replied the Doctor. "Most people don't understand that. You see, there are two distinct processes by which we turn food to account in building up our bodies, making strength and heat, and generally carrying on the processes of life. One of those processes is digestion, and the other assimilation. Digestion simply reduces the food which we have eaten to a condition in which it can be assimilated. By assimilation certain organs of the body take up the food thus prepared for them, convert it into blood and send it through the system to nourish it. In the passage of the blood through the arteries and veins, it leaves deposits of muscle here, fat there, bone in another place, and so on. This is a very rude statement of the matter, but it is sufficient to show you what I mean, at least in a general way. Very well. It does a man no good whatever to digest his food if he doesn't assimilate it. No matter how perfectly the stomach does its work, the body is not nourished unless the organs charged with the function of assimilating the digested food do theirs also. Once, in a hospital, I saw a little baby die of actual starvation, although it had an abundance of food, and digested it perfectly. It simply could not assimilate."
"But what has that to do with our going to bed at two o'clock in the morning?" asked Jack, who was disposed to be a trifle cross as the result of the long starvation and strain.
"Only this," answered the Doctor, "that unless we give our weakened stomachs a little chance to digest our food properly before we go to sleep, the process of assimilation will be very imperfectly performed and we shall not be as perfectly nourished as we need to be. Still, I think we might safely go to bed now," added the Doctor, "as the half hour is gone, and it is now two thirty"—looking at his watch.
With that the exhausted company prepared for bed. Jim Chenowith was the first to approach the bunks, under which the earthen floor was a little lower than in the rest of the cabin. As he did so, having slipped off his boots, Jim called out:
"Hello! What's this? I say, fellows, we have a creek here under our beds!"