CHAP. IX.] 



THE CONTRACTILE TISSUES. 



403 



During this time the animal was kept wrapped up in wadding to prevent 

 such an excessive cooling as might of itself depress the tissue-changes. 

 Artificial respiration was carried on at the same rate as before. Under 

 these circumstances both the consumption of O and the excretion of C0 3 

 were diminished by more than one-half in the course of an hour or two. 

 Thus l in one case the consumption of O fell 



from 1740 cm. to 750 cm. per hour; 

 the excretion of CO 2 fell 



from 1560 cm. to 591 cm. per hour. 



The diminution observed by PMger and others 2 working in his 

 laboratory, as the mean of many experiments, was somewhat less than 

 this, viz. 



Normal rabbit 

 Curarized rabbit 



that is to say, 



in the amount of O 35 '2 p.c. 



in the amount of CO 2 37 "4 p.c. 



This diminution of the gases interchanged in respiration is not 

 due to a deficient circulation; for both the blood-pressure and the 

 heart were observed in similar experiments to be unhampered and 

 normal. Nor can it be set down to the cessation of the ordinary 

 muscular contractions of repose, viz. those of respiration and those 

 which serve to maintain the upright position ; unless, indeed, they 

 are assumed to have unexpected proportions. It might be caused by 

 some direct action of the curare upon the tissues which give rise to 

 carbon dioxide in the body ; and experiments were undertaken by 

 Colasanti 3 to test this supposition. Curarized and non-curarized blood 

 was made to traverse, under precisely similar conditions, the right 

 and left hind limbs respectively of a recently killed muscular dog. 

 On comparing the outflowing blood from the two limbs it appeared 

 that there was no difference in the relative proportions of oxygen 

 and carbon dioxide contained in them. Hence the diminution must 

 be due to some influence of the central nervous system which is cut 

 off when the animals are paralysed by curare. 



The experiments in which the spinal cord was divided shewed that, 

 even when the respiratory muscles were left freely acting, the separation 



1 Zuntz, Op. cit., p. 527. 



2 Pa tiger, Op. cit. Archiv f. d. ges. Physiol., Vol. xvin., 1878, p. 302. Finkler und 

 Oertmann, Archiv f. d. ges. Physiol., Vol. xiv. p. 62. 



3 Giuseppe Colasanti, "Zur Kenntmss der physiologischen Wirkungen des Curare- 

 giftes." Pfliiger's Arch. f. d. ges. Physiol., Vol. xvi., 1878, p. 157. 



262 



