RESPIRATORY CENTRE IN THE SPINAL CORD. 323 



not extend to the spinal cord; l)ut the recent researches of 

 Prokop Eokitansky (Strieker's Medicinische Jahrhilcher, 1874, 

 p. 30) on this subject show how careful we must be in drawing 

 conclusions from experiments. Like all others, he has found that, 

 under normal conditions, breathing ceases as soon as the influence 

 of the medulla is destroyed by division of the cord just below 

 it. But if stryclmia be given to the animal, so as greatly to 

 increase the excitability of its respiratory centre as well as of 

 other reflex centres before the cord is divided, respiration will 

 go on after the section has been made ; and strychnia injected 

 into the veins after the section will restore the respiratory 

 movements, which the cut had arrested. This shows that the 

 respiratory centre is not confined to the medulla, but extends 

 into the spinal cord. The part contained in the cord is, how- 

 ever, too weak to keep up respiration alone under ordinary 

 circumstances, though it can do so when its power is increased 

 by strychnia. These remarkable effects of this poison give 

 promise of future benefit from its use as a restorative in cases 

 of death from drowning, &c. ; but further experiments on 

 animals are necessary before we dare employ such a power- 

 ful remedy in man. 



Eokitansky's experiments enable us to demonstrate the 

 presence of a respiratory centre in the spinal cord, as well 

 as in the medulla of adult animals ; but it is only fair to say 

 that this was showm long ago by Brown-Sequard in the case of 

 young ones. In young mammals and adult birds, he found that 

 the thorax continued to execute rhythmical respiratory move- 

 ments for a short time after the cord had been divided trans- 

 versely at the level of the first or second pairs of cervical 

 nerves, so that there must needs be a part of the respiratory 

 centre in the cord below that level {Journal de la PhTjsiologie^ 

 vol. i, 1858, p. 228, and vol. iii, 1860, p. 153). Besides this, 

 he considers that there are what we may term peripheral 

 respiratory centres — viz., ganglia in the substance of the 

 diaphragm itself analogous to those in the heart, which enable 

 it to contract rhythmically after its connections both with the 

 medulla oblongata and with the spinal cord have been destroyed 

 (pjp. cit., vol. ii, 1859, p. 115). 



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