LOCAL NERVE CENTRES. 671 



posterior roots. On the other hand, neither Vulpian 1 nor Kuhlwetter 2 

 found any effect. 



Gartner 3 confirmed Strieker, and insisted on the necessity of the 

 precautions pointed out by Strieker, namely, young dogs, no curari or 

 anaesthetics, stimulation by ligature and not by the interrupted current, 

 previous section of the thoracic cord. 



Since none of these precautions are necessary in the case of the 

 known vaso-dilator nerves, it follows, so far, that however the rise of 

 temperature is produced, it is not produced by the action of ordinary 

 vaso-dilator nerves. 



The question was taken up by Morat. 4 He observed the colour of 

 the hairless, unpigmented parts of the foot in the dog and cat. Accord- 

 ing to him, the only precaution necessary is that the animals should be 

 young. Werziloif, 5 returning to the use of the thermometer and using 

 also the plethysmographic method, again confirmed Strieker's results. 

 He apparently did not find necessary any of the special precautions 

 mentioned by Strieker and Gartner. 



Since in numerous cases in anaesthetised cats I have not found any 

 flushing in the foot, on stimulating the nerves which run to the fore- and 

 hind-limbs, I am inclined to attribute the rise of temperature and 

 flushing, which has been observed by others on stimulating the posterior 

 roots, to some other cause than the stimulation of vaso-dilator fibres in 

 these nerve roots. 



One fact which has been overlooked in experiments on this question, is the 

 possibility of an escape of current to the ramus of the nerve. This takes 

 place much more readily in young than in old animals, and it is curious 

 that three out of the four observers who have found positive effects, lay stress 

 on the advantage of experimenting with young animals. It is also more 

 likely to occur the stronger the stimulation, and, according to Morat, strong 

 stimulation is required. On the other hand, we should expect that an escape 

 of current to the grey ramus would take place as readily when the anterior roots 

 are stimulated as when the posterior roots are stimulated. But all observers 

 find slight or no effects with the anterior roots. It may be objected also that 

 an escape of current to the grey ramus would cause a fall of temperature, and 

 not a rise ; this is to a certain extent true, but the rise might be due to an 

 after-dilatation of the vessels. There are also other ways in which, in the 

 conditions of the experiments, vascular dilatation might be produced, although 

 there were no efferent vaso-dilator fibres in the posterior roots. It would, 

 however, take up too much space to dwell on the various possibilities. It is 

 sufficient to say that the existence of these fibres has not yet been proved, and 

 that, as the question is one of considerable importance, it is most desirable that 

 further careful experiments should be made. 



LOCAL NERVE CENTRES OTHER THAN THE CRANIAL, SYMPATHETIC, 

 AND SACRAL GANGLIA. 



Goltz, 6 in experiments on dogs, found that section of the sciatic 

 nerve did not cause a permanent rise of temperature in the foot, but 

 that the temperature returned to normal in a week or two. He dis- 



1 Arch, dephysiol. norm, et path., Paris, 1878, p. 336. 



2 Beitr. z. Anat. u. Physiol. (EcTchard), Giessen, 1885, Bd. xi. S. 25. 



3 Wien. klin. Wchnschr., 1889. 



4 Arch, dephysiol. norm, etpath., Paris, 1892, p. 689. 



5 Centralbl.f. Physiol., Leipzig u. Wien, 1896, Bd. x. S. 194. 



6 Arch.f. d. ges. Physiol., Bonn, 1875, Bd. xi. S. 92. 



