ARREST 131 



case it is to be remembered that the foetus enjoys a moist 

 environment, and that probably for this reason the surface 

 exposed after limb removal is able to replace lost tissue- 

 cells to a degree impossible in aerial extra-uterine environ- 

 ment, where desiccation is hostile to growth. We may say 

 that the watery environment of the womb makes restora- 

 tion of the arm a possibility, and that an assistant factor 

 would be the youth of the tissues. But why is restoration 

 incomplete ? 



A not unlikely explanation is as follows : The central 

 control of the foetus develops in harmony with the mass 

 of the body-plan which it controls. When the fcetal arm 

 was amputated the control-centre had evolved the capacity 

 of governing the further development of an already formed 

 arm, and was not perfectly adapted for controlling the 

 formation of a new one. It may be that for this reason a 

 certain amount of past development could not be repeated, 

 and similarly we might judge that what prevents the res- 

 toration of the lost finger of an adult is the fact that the 

 adult's control-centre is for the government of the mature 

 finished plan, and not for that of the evolving plan. In 

 addition, it is to be noted that after fcetal arm-amputation 

 the exposed cells of the stump, whose multiplication would 

 produce the new dwarfed limb, would be descendants of, 

 and more maturely differentiated than the cells which 

 originated the amputated limb in the first place. Their poten- 

 tialities would, it is to be presumed, be correspondingly less. 



To recapitulate. Continuity is instrumental in arresting 

 a certain part of the developing Individual, so that this 

 part evolves on side-lines and never originates or becomes 

 sexual elements ; it becomes the arrested or fixed species 

 of the somatic tissue cells. And Continuity also arrests 

 the multiplication of the somatic cells in accordance with 

 the needs of body equilibrium. Lastly, a breach of tissue 

 Continuity is followed by a species of release from arrest in 

 the form of special local cell multiplication to repair the 

 breach. This multiplication is under control, local, but 

 ultimately central, and arrest is reapplied, also under control, 

 when the breach is repaired. It will be necessary to return 

 to this in connection with abnormal growth. 



