68 University of California Publications in Anatomy [Vol. 2 



entire soraato-sensory cortex. So far neither experimental studies 

 with animals and with conscious patients nor pathological clinical 

 investigations have brought that problem nearer to its solution. (Vogt, 

 [1919] has made probable that in certain motor performances of the 

 precentral gigantopyramidal area there is a collaboration of all cortical 

 layers of this area or a portion of it in producing special motor acts.) 

 The previous cytoarchitectural studies and the areal and regional dif- 

 ferences in the character of the intracortical afferent fibers found in 

 the present investigations harmonize rather well with the assumption 

 of areal and regional differences in the function of the somato-sensory 

 cortex. According to my view, each precentral and postcentral cyto- 

 architectural area would be endowed with its own special component 

 of a primitive, elementary quality of sensibility not identical with that 

 of the other somato-sensory areas. (Whether these primitive qualities 

 are identical with those distinguished by physiology, psychology, and 

 pathology has to be determined by further experimental investigation, 

 by separate ablation of definite cytoarchitectural areas, and by clinical 

 and pathological investigations.) Yet this would in no way exclude 

 the possibility that in the subjective realization of a special form of 

 sensation the roles of certain cell layers of a given area would be 

 different. (Compare also Vogt, 1919, p. 440.) In other words, for 

 the subjective experience of different forms of somatic sensation cor- 

 tical elements differing in shape, size, number, distribution, and con- 

 nections are required. Thus, by way of hypothesis, the granular layer 

 of the postcentral cortex would be indispensable for the exteroceptive 

 forms of somatic sensation and that form of proprioceptive sensibility 

 bearing a more conscious character; the agranular precentral cortex, 

 on the other hand, would be subservient to a form of the proprioceptive 

 sensibility remaining largely unconscious. Such an assumption of 

 differences in receptive function between the precentral and the post- 

 central region would also be in good accord with Vogt's (1919, p. 458), 

 Flechsig's (1920, pp. 18, 38), and Minkowski's (1923-24) findings of 

 the differences in connections between the precentral and the post- 

 central regions. According to Vogt, the precentral area 4 is related 

 to the anterior portion of the thalamus where tegmento-thalamic fibers 

 terminate, while the postcentral region receives fibers from the poste- 

 rior portion of the thalamus where the median fillet terminates. (Com- 

 pare also Quensel, 1909, 1910; Meyer-Muller, Tsunesuke Fukuda, 

 Flechsig, 1927, pp. 79, 80, 81, 111, and Bonhoeffer, 1928.) 



Considering the results of the present investigations it might be 

 easier to understand what obstacles until now have prevented a satis- 



