[The tumor as an atavistic adaptive reaction in environmental conditions]

In sponges, coelenterates, bryozoans, and ascidians, blastogenesis associated with the formation of resting buds and resting blastogenetic structures is similar to the oncogenesis. Just as the tumours, such buds and structures: 1) when released from control of the parent organism, developed independently of the latter and cause its destruction; 2) originate due to the action of various external and internal causes; 3) are hardy to anoxia, dehydration, overcooling; 4) consist of little differentiated and de-differentiated cells. These similarities can be explained in the frame of hypothesis which considers tumours an atavistic resting structure.