It has already been shown (1) that tissue cells growing in vitro are not independent cell-individuals, but form tissues and grow as a whole, forming a partial undifferentiated organism. It was concluded that the anastomosis between the individual cells found in vivo as well as in vitro is significant for the regulation of their growth. A special method was developed which made it possible to distribute the cells individually in a suitable medium. Cell-division was never observed to occur in isolated cells, neither was development of a cell colony from a few scattered cells observed to take place.