In a previous article1 the motor surface areas of the cat, dog, monkey and man were measured, and certain relationships were shown. This area was chosen first because of its grosser characteristics and its easier delimitation.
German writers contributed extensively in the field of mensuration and cyto-architecture in different animals. Brodmann2 studied the cortical fields in the animals that are most commonly employed in laboratory experiments. Gurewitsch, Chatschaturian and Chatschaturow,3 in 1928, devised a new method for measuring cortical fields in their studies on the cat which is somewhat analogous to the method described by Kraus, Davison and Weil.4 They made use of parallel sections, and the side surface of each single section was equal to the surface area of a trapezoid. The length of the parallel sides of the trapezoid corresponds to the length of the contours which border the section. The height of the