LATERAL SEMISECTION OF THE CORD. 865 



path employing the two halves of the cord, 1 though the major division 

 descends on the side homonymous with the peripheral sense organs. 2 

 Bilaterality of the path was next accredited 3 as well to the descending 

 spinal conduction for intentional movement of the skeletal musculature 

 of each side-half of the body; the homonymous path was stated as in 

 sensation to be the chief one, that is, the side homonymous with the 

 musculature innervated. It was noted, 4 especially in the frog, that the 

 impairment of the volitional motility and of the sentient function of the 

 limb is, when the semisection lies though headward yet near to the 

 nerves to the limb, greater than when placed further forward. After 

 semisection in the cervical region, a certain power of volitional move- 

 ment is retained for the hind-limb homonymous with the semisection. 

 Attention was drawn, especially by the long series of experiments by 

 Chauveau, 5 to a great contrast existing in the homonymous side, between 

 heightened reflex activity and defect in true sensifacient power. This 

 increase of reflex excitability was noted to gradually increase rather 

 than to subside with time. It was also observed that the temperature 

 of the homonymous hand and foot (skin) rises after cervical semisection, 

 but that the temperature of the axilla and groin falls (muscle). 6 



In a series of experiments by Weiss 7 the difference between early 

 and late symptoms was carefully recorded, the semisection lying at the 

 hindmost thoracic segment in the dog. The exact extent of the lesions 

 was verified by subsequent microscopical examination. (1) On the 

 homonymous side the condition for the first day or so was : Motor poiver ; 

 " volitional " gone, reflex greatly impaired ; the hind-limb hangs extended 

 at knee and ankle, adducted at hip : Sentient poiver ; very defective. 

 Later, in the course of some weeks, there ensued restoration of func- 

 tion : motor power, for standing, walking, running, became almost 

 perfect, and the movements of the affected limb were well associated 

 with the movements of the other limbs. As regards the sentient 

 functions, mechanical and electric stimulation of the skin and of 

 the nerve trunks of the limb showed deficiency ; movements evoked 

 reflexly in the limb by skin stimuli, though often vigorous, were never 

 accompanied by whining. (2) In the contralateral limb the motility 

 was at first somewhat impaired, but was soon restored to normal. The 

 sentient functions, at first markedly depressed, as compared with the 

 fore-limb, in course of time returned in part, though permanently sub- 

 normal. The sensory defect exists, according to Weiss 8 and Botazzi, 9 

 for all kinds of cutaneous sensation and for " muscular." A second semi- 

 section practised after recovery from the first, and on the opposite side 

 one spinal segment further headward, abolished permanently motility 

 under " volition " and all sentient power in both hind-limbs, and in as 



1 v. Deen, "Physiol, d. 1. moelle e'piniere " (frog), Leide, 1841. 



2 Budge, "Einfiuss d. Centraltheil. d. Nervensystems " (cat and frog), 1842, S. 157. 



3 Stilling, "Funct. d. Riickenmarkes '" (cat), 1842. 



4 Eigenbrodt, "Die Leitungsgesetze d. Riickenmarks " (frog and dog), 1849 ; Kolliker, 

 Gzermak, and Corti (rabbit), " Mikr. Anat.," Leipzig, 1850, Bd. i. S. 438; v. Bezold, 

 "Ueber d. gekrenzt. Wirkung. d. Ruekenmarkes " (frog, pigeon, rabbit, guinea-pig, cat, 

 dog), Berlin, 1859. 



5 Monit. d. hdp., Paris, 1857, p. 1005. 



6 v. Bezold, op. cit. (cat and dog), 1859; see also SchifF, "Lehrbuch d. Nerven- 

 system," 1858-1859, S. 272 ; and Mott, Phil. Trans., London, 1892. 



7 Sitzungsb. d. k. Akad. d. Wisscnsch., Wien, 1879, Bd. lxxx. Abtli. 3. HomeVs 

 experiments (Helsingfors, 1885) yielded results on the dog identical with those of Weiss. 

 The secondary degenerations were carefully studied as well as the functional condition. 



8 Loc. cit. 9 Centralbl.f. Physiol., Leipzig u. Wien, 1894, S. 530. 



vol. ii.— 55 



