Passage Two Every human being has a unique arrangement of the skin on his fingers and this arrangement is unchangeable. Scientists and experts have proved the uniqueness of fingerprints and discovered that no exactly similar pattern is passed on from parents to children, though nobody knows why this is the case. The structure on a person's fingers does not change with growth and is not affected by superficial injuries. Burns, cuts and other damage to the outer part of the skin will be replaced in time by new skin which bears a reproduction of the original pattern. It is only when the inner skin is injured that the arrangement will be destroyed. Some criminals make use of this fact to remove their own fingerprints but this is a dangerous and rare step to take. Fingerprints can be made easily with printer's ink. They can be recorded easily. With special methods, identification (辨识) can be achieved successfully within a short time. Because of the simplicity and economy of this system, fingerprints have often been used as a method of solving criminal cases. A suspected man denies a charge, but his fingerprints can prove who he is even if his appearance has been changed by age or accident. When a suspect leaves fingerprints behind at the scene of crime, they are difficult to detect with the naked eye. Special techniques are used to 'develop' them. Some of the marks found are incomplete but identification is possible if a print in the size of a quarter of an inch square can be obtained. Which of the following is NOT true of fingerprints?