Experiments on the possibility of cultivating tissue cultures on media containing starch instead of glucose have led to starch strains derived from a crown-gall strain of Nicotiana tabacum and from a normal cambium strain of Rubus fruticosus. Started in 1953, to date 42 and 28 passages respectively could be accomplished by uninterrupted cultivation on starch media. A substrain of Nicotiana on starch medium has been cultivated in darkness through 31 passages. Cultivation on starch media could be accomplished because of the activity of amylases given off by the cultivated tissues. The presence of an a-amylase and possibly a could be established. The phenomenon has been described that growth habits on glucose and starch media are strikingly different. Transfer back to glucose medium results sooner or later in the restoration of the glucose growth habit. In a separate paper, the changes in growth habit, the observed changes in growth pattern, and particulars about the internal structure will be discussed. Biochemical aspects of the phenomenon described are under investigation.