|
|
On average, the stomach produces 2 L of hydrochloric acid per day.
Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.
Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.
Not getting enough sleep can greatly weaken the immune system. Lack of sleep makes you more likely to catch a cold, or more difficult to fight off an infection.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
![A passenger train crosses Stony Creek Bridge in the Rocky Mountains in 1878. Railroads were importan](https://biology-forums.com/gallery/47/medium_27_24_08_15_1_27_03_22389406.jpeg)
![On May 15, 1916, after deliberating for one hour, an all-white jury in Waco, Texas, found seventeen-](https://biology-forums.com/gallery/47/medium_376716_26_08_15_11_19_28_224611295.jpeg)