In 5 human brains (9 hemisphares) the distribution area of Betz cells were extended in a plane and their distributing density was studied. 1) The extended diagrams showed an irregular elliptic shape in each hemisphare without regard to the directions of the gyri. 2) In case of the same person the diagram was larger in the dominant hemisphare. 3) The distributing density of Betz cells was also larger in the dominant side. 4) Generally the Betz cells were found less in the ridges of the gyri and more in the bottom. 5) Campbell's suggestion that there are 7 groupings of Betz cells was not justified, but the distributing density was not homogenous even in the area of dense distribution. From the facts above mentioned, if it is considered gyri are made passively when the brain grows in a limited cranium, it is concluded that, the distributing area of Betz cells may be placed posterior to the central sulcus or be hidden in the bottom of the sulci and the gyrus can not be the standared for the determination of localisation of the cerebral areas.