( 310 ) 



with the analgetic areas called into existence by the destruction of 

 sensibility in one or more segments. 



A few instances may serve to illustrate this. The sensibility of 

 the skin under normal circumstances is strongest within a system 

 of lines and zones, corresponding with the average limits of the 

 dermatoma (of more precise limits we cannot speak because of the 

 overlapses). This has been proved clinically for man by Langelaan ^), 

 experimentally for the dog by Winkler ") and myself. Now if we 

 observe the dark stripes of the zebra, we find that beyond any 

 doubt these stripes, at least on neck and trunk, show a marked 

 accordance in their distribution and direction with the average limits 

 of the dermatoma, as these latter may be imagined to be, relying 

 on the data procured by Peyer '), Sherrington ^), Türck ^), Winkler ") 

 and myself respectively for tiie rabbit, the monkey and the dog. 



Their number corresponds nearly with that of the segments of 

 neck and trunk; on the neck and on the trunk they are somewhat 

 wider apart than at the points of insertion of the extremities, this 

 being in perfect accordance with the fact demonstrated by Winkler 

 and myself that at those points the ranks of the dermatoma are more 

 thickly set. The distribution of the stripes on the extremities is not 

 so easily explained. On superficial view they resemble rings, 

 running around the extremity. In reality however each of these rings 

 consists of two symmetrical semicircles, passing by pairs into one 

 another by a definite angle on the outside and on the inside of the 

 extremity. Connecting together the different points at which the semi- 

 circles meet, we obtain two lines corresponding with the dorsal and the 

 ventral axis-lines of the extremity. The direction in which the stripes 

 run (in a caudal direction from the axis-lines), corresponds with 



1) J. W. Langelaan, On the determination of sensory spinal skinficlds in heallliy 

 individuals. These Proc. Ill, p. 251. 



2) See note 1 on the preceding page. 



3) J. Peyer, Ueber die peripheren Endigungen der motorisclien und sensibelen 

 Fasern des Plexus bracchialis. Zeitschrifl f. rat. Medizin. N. 7, Bd. IV, 1854, S. 52. 



^) G. S. Sherkington, loco citato, and: Idem II Ibidem vol. 190, B. 1898, p. 45—186. 



3) L. Türck, Vorlaufige Ergebnisse von Experimental Untersuchungen zur Ermit- 

 telung der Hautsensibililatsbezirke der cinzelnen Rückenmarksnervenpaare. Sit- 

 zungsber. der K. K. Akad. der Wissensch. zu Wien 1856, and: Die Hautsensibili- 

 tatsbezirke der einzelne Rückenmarksnervenpaare. Aus dem literarisclien Nachlasse 

 von weil. Prof. Dr. L. Türck zusammengeslellt von Prof. Dr. G. Wedl. Denk- 

 schriften der Math. Naturw^. Glasse der K. Akad. der Wissensch. zu Wien. Bd 

 XXIX, 1869. 



^) G. Winkler and G. van Rijnberk, On function and structure of the trunk- 

 dermatoma 1. These Proc. Vol. IV, p. 266; II. 1. c. p. 308; III. 1. c. p. 509; IV. 

 1. c. Vol. VI, p. 347. 



