OF THE CALABAR BEAN. 



743 



thorax and abdomen were well filled, and could be readily distinguished by the colour of their 

 contents. On incising the left ventricle, blood of the usual arterial hue escaped ; and on incising 

 the right, dark blood appeared. Both were allowed to run side by side, when the contrast was 

 distinctly shown."* 



We have now to describe the various changes that are undergone by the heart 

 before its contractions finally cease, and to examine the mechanism by which these 

 changes are produced. For the former purpose, several experiments were per- 

 formed on frogs whose hearts were exposed before the administration of the poison. 



Experiment XLYII. — {Temperature of Laboratory, 58° F.) 

 A large frog, which weighed 730 grains, was fixed down on its back in such a manner that 

 the circulation in the limbs was not to any extent impeded ; and the heart was exposed by the 

 removal of a portion of the sternum. This operation can easily be performed without injuring 

 any large blood-vessel, and, indeed, without causing any loss of blood further than a temporary 

 oozing from the cut surfaces. A few minutes afterwards, its heart-beats were frequently counted, 

 and found to average seventy per minute. I then injected one grain of extract, mixed with a 

 little water, into each thigh (two grains in all). 



5 minutes afterwards, cardiac contractions = 64 per min. 

 10 



15 



20 

 25 

 30 

 35 

 40 

 45 

 50 

 55 

 1 hour 



min. 

 5 



10 

 15 

 20 

 30 



40 



1 „ 50 



2 hours 



2 „ 10 



2 „ 30 



3 „ 



3 „ 30 



4 „ 

 4 „ 30 



= 58 

 = 43 



= 39 

 = 41 

 = 37 

 = 24 

 = 22 

 = 22 

 = 19 

 = 13 

 = 14 



= 12 



= 10 

 = 9 

 = 9 

 = 10 



= 10 



= 8 



12 

 18 

 21 



24 



= 26 



f Eespirations ceased, except an ceca- 

 ls sional gasp. 



No respiratory movements. 



Contractions feeble. 



Skin much darker than originally. 



r Heart equally dark in systole and 

 \ in diastole. 



c Galvanism of sciatics caused neither 

 X direct nor reflex contractions. 

 v Muscles dark bluish, and active. 



Surface of heart opal blue in colour. 



Cardiac contractions extremely feeble. 

 f Skin deep olive-brown : the frog was 

 \ originally a pale one. 



Spinal nerves still perfectly paralysed. 



f Cardiac contractions quite synchron- 

 ic ous, and diastole prolonged. 



{ 



VOL. XXIV. PART III. 



A faint twitch occurred when 

 left sciatic was galvanised. 

 Op. cit. section v. experiment iii. 



9 Q 



the 



