362 SIR THOMAS R. FRASER AND MR ALISTER T. MACKENZIE ON 



the flanks become alternately distended by several inspirations and then flaccid with a 

 single expiration ; and respiratory movements of the throat occur after those of the 

 flanks have ceased, and can be observed when no cardiac impact is visible. Signs of 

 muscular weakness are soon manifest, all the extremities become loosely flexed, the 

 thorax and abdomen rest on the surface of the tray and the muzzle sinks down. When 

 this weakness first appears, jumping can still be performed fairly well, and the frog 

 recovers the prone position rapidly when placed on the back. Subsequently, jumping 

 is effected with difficulty and the frog is unable to raise its body completely off the 

 surface of the table, and it makes no visible spontaneous effort to recover the prone 

 position when lying placed on the back. Reflex movements may still be obtained, but 

 the reflexes are less acute. Careful examination of the precordia does not reveal any 

 cardiac impact, and, if the thorax be opened, the heart is usually found to be motionless, 

 the ventricle is pale and small and does not respond to mechanical stimulation, the 

 auricles are usually very large and dark, and they may be quite motionless or feebly 

 contracting upon their contents, but their movements fail to produce any visible change 

 in the condition of the ventricle. Soon afterwards, the heart is found to be motionless, 

 pale and small, its contractility quickly disappears and the ventricular muscle gives an 

 acid reaction when tested with litmus paper. The conjunctival reflex may be present 

 after the heart has ceased to contract, and the pupils are at that time of small size. 

 The skeletal muscles are contractile for a short time after death, but become acid in 

 reaction soon after the heart muscle, and general rigor very soon sets in and is well 

 marked, especially in the anterior extremities and the anterior parts of the trunk. 



Summary of General Effects in Rats. 



As already indicated, rats are peculiarly resistant against even large subcutaneous 

 injections of the extract. When the dose is such as is sufficient to cause death in four 

 hours, restless movements occur at first, and recur at considerable intervals, and between 

 them drowsiness and inactivity are manifested. The respirations become slower, more 

 deep, and laboured and heaving in character, and expiration is more prolonged than inspira- 

 tion and is often interrupted. In some cases (Experiments XIX. and XXIII. ), sudden 

 interruptions of expiration occur in the course of the experiment, and the thorax appears 

 to be fixed during attacks of dyspnoea. These symptoms may be compared with the 

 ballooning of the flanks in frogs. Signs of muscular weakness develop early, and the rat 

 becomes unable to climb up the side of the tray, its muzzle rests on the surface of the 

 tray and, when the animal moves, it drags its hind-limbs ; still later, voluntary move- 

 ments become more impaired and are accompanied with clonic spasms ; and, finally, the 

 animal becomes paralysed, general convulsions occurring immediately before death. 



Summary of General Effects in Rabbits. 



When a dose sufficient to cause death within four hours is given subcutaneously to 

 a rabbit, the first change usually observed is a temporary flattening of the back, which 



