Artificial meat — grown in a test tube from animal stem cells — has been theoretically planned for about 10 years, but a European Science Foundation audience heard predictions that lab-grown sausage might be available as soon as next year. The meat is produced in sheets (“shmeat”) and would be prohibitively expensive at first, in that the largest specimen produced so far measures only about one inch long and a third of an inch wide. The biggest drawback facing artificial muscle tissue: that even lab-grown muscles require exercise to prevent atrophy.