1884.] Experimental Researches in Cerebral Physiology. 439 



up-turned end of the calloso-marginal sulcus on the mesial surface. 

 Behind the furrow of Rolando and opposite this end of the calloso- 

 marginal furrow there is a small, but constant, obliquely-placed 

 depression (fig. 1, z), which serves to mark the separation between the 

 ascending parietal gyrus and the parietal lobule. In front of the 

 furrow of Rolando, and separated from it by the upper end of the 

 ascending frontal gyrus, is another small depression (a?), also extremely 

 constant in occurrence, although varying considerably in develop- 

 ment, having a direction parallel to the margin of the hemisphere, 

 from which it is a few millimetres removed. Still further forward, 

 and at a much greater distance from the margin, is the well-marked 

 transverse frontal furrow, the antero-posterior limb of which (tr.fr} is 

 shown in the figure. And in front of this again is another small and 

 apparently unimportant depression (fig. 1, ?/), but very constant in the 

 Macacques, which has a transverse direction, i.e., perpendicular to the 

 hemisphere-margin, and which, in some instances, comes nearly up to 

 the margin, conducting a considerable vein towards the longitudinal 

 sinus. The excitable portion of the marginal convolution extends 

 from about opposite this small transverse sulcus (F) backwards along 

 the whole length of the convolution. In front of the level of the 

 sulcus y no movements £11*0 j ELS £L rule, obtained as the result of electri- 

 cal excitation. 



A remarkable relation was found on the whole to hold good 

 between different parts of this convolution and the parts of the 

 body thrown into movement by their excitation, to the effect, namely, 

 that when the stimulus was applied anteriorly the resulting move- 

 ments affected the upper limbs (and in one or two instances muscles 

 of the head and neck) ; when applied near the middle of the excitable 

 part of the convolution, the muscles chiefly or primarily affected were 

 those of the trunk (erector spina?, abdominal muscles, &c), whilst, 

 when applied posteriorly, muscles of the lower limb alone were called 

 into action. Indeed, it appears probable that, if we regard only the 

 results of minimal excitations, and especially if we take into account 

 only those muscles which are primarily called into action, this rule will 

 prove to obtain in a still more special manner, and that we may arrange 

 the movements which are produced by stimulation of points which 

 succeed one another from before back in the following order, viz. : 

 1. Movements of the forearm. 2. Movements of the humerus and scapula. 

 3. Movements, chiefly rotation and flexion, of the upper part of the 

 trunk. 4. Movements of the lower part of the trunk and abdomen. 

 5. Movements of the pelvis. 6. Movements at the hip. 7. Move- 

 ments at the knee. 8. Movements at the ankle-joint. 9. Movements 

 of the toes. 



The general results of our experiments will best be understood by a 

 reference to the accompanying figure (fig, 1). Thus, in the part of 



