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Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.
Cocaine was isolated in 1860 and first used as a local anesthetic in 1884. Its first clinical use was by Sigmund Freud to wean a patient from morphine addiction. The fictional character Sherlock Holmes was supposed to be addicted to cocaine by injection.
The heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.