Ciliate conjugation is a sexual phenomenon that results in genetic recombination and nuclear reorganization within the cell. In most ciliate groups, however, the cells separate after conjugation, and both form new macronuclei from their micronuclei.
Before the bun, hamburgers are said to have been served between two pieces of bread. In fact, a ground beef patty was known as Hamburger steak (first mentioned in an American cookbook in 1891); when this was put between bread or in a bun it was called a Hamburger sandwich.
The hamburger most likely first appeared in the 19th or early 20th century. The modern hamburger was a product of the culinary needs of a society rapidly changing due to industrialization and therefore having less time to prepare and consume meals. Americans contend they were the first to combine two slices of bread and a steak of ground beef into a hamburger sandwich and sell it.