180 



JOSEPH DUERSON STOUT 



cus cruciatus is better displayed. Then, anteriorly, the area extends 

 downwards and outwards, to be limited in turn by the upper extremity 

 of the orbital and the anterior extremity of the coronal sulcus. Later- 

 ally, the sulcus coronalis constitutes a bar, transverse sections showing 

 that formation reaches to the floor of, but not beyond, the sulcus. 

 Posteriorly, the field meets the post-crucial or sensory area medially, 

 across the hinder line of the "sigmoid gyrus, and it is most important 

 to observe that the boundary line is constantly related to a shallow 

 depression, placed equidistant from the cruciate and ansate sulci. 

 This depression varies in representation in different brains and even 

 in opposite hemispheres. It may appear as a short transverse fissur- 

 ette, or merely as a dimple, but it is never entirely absent, and I have 

 little doubt that it is the equivalent of a fissurette better developed in 

 other animals and known as the Compensatory Ansate. 



(a) 



FIG. 2. Motor area of cat's cerebrum (cross-hatched), as differentiated by 

 cyto- and myelo-architectonic methods (adapted from Campbell). 



He makes further reference to the homology of this fissure. 



There have been few satisfactory descriptions of the physio- 

 logical conditions existing in the brain of the cat, which are 

 available for the study of the motor control. The most satis- 

 factory accounts are those published by Ferrier in 1886 and by 

 Frangois-Franck in 1887. 



Ferrier made numerous investigations of the motor area in the 

 cortex of the cat. In stimulation experiments he used the in- 

 duced current of sufficient strength to cause "a pungent but 

 quite bearable sensation when the electrodes were placed on the 

 tip of the tongue." He states that 



Though it is obviously advisable to use no stronger current than is 

 sufficient to produce a definite result, the measure of the intensity of 



