300 PROFESSOR C. R. MARSHALL ON 



slowing may reappear for short intervals independently of any obvious convulsive 

 action (fig. 3). Later, if the dose has been sufficient, the respiration becomes irregular 

 in extent, although it usually retains a fairly regular rhythm. This condition may 

 continue for a long period, but finally it leads to deficient aeration and to cessation of the 

 respiration. Variations in the respiratory tracings have occurred. In two instances a 

 regular alternation of shallow with slower deep respirations developed ; in other cases 

 the respirations during the absence of convulsions were characterised chiefly by 

 prolonged inspirations. The influence of the convulsions on the respiration during 

 anaesthesia was relatively slight. Sometimes a diminution in the frequency of the 

 respirations accompanied the convulsion, but generally no distinct change in the 

 respiratory rhythm occurred. The convulsions in these experiments were purely 

 clonic in character. 



During anaesthesia the circulation also is very little influenced by the administration 

 of moderate doses of tutin, or even by the convulsions produced. When chloroform 

 was employed as the anaesthetic a slight rise of blood pressure and slowing of the 

 heart's frequency followed the injection of the drug and coincided with the effect on 

 the respiration, but not infrequently neither blood pressure nor heart rate was 

 changed. With ether as anaesthetic a rise of blood pressure and a diminution in the 

 frequency of the heart were more common, and were greater in extent than with 

 chloroform. The difference in all probability is mainly due to the lighter degree of 

 anaesthesia produced in rabbits and cats by ether. Of the three chief medullary 

 centres, the vasomotor appears to be least susceptible and the respiratory the most 

 susceptible to tutin injected during anaesthesia. 



The Convulsions. 



The convulsions produced by tutin are typically epileptiform in character. After 

 a non-lethal but convulsant dose the earliest manifestations of the convulsant action 

 of the drug are rapid head-noddings, or tremors of other parts of the body, and an 

 increase in tone of the muscles, and especially of the limb muscles. These tremors 

 are followed by clonic movements terminating in a tonic spasm. The clonic spasms 

 commence, in the early convulsions generally, and in the later convulsions always, 

 in twitches about the face and head — in movements of the mouth, or winking of 

 the eyes, or twitching of the ears — which may at first be unilateral. There may be 

 also rotation of the head to one or other side. Then follow clonic movements of the 

 fore limbs and later of the hind limbs, and the termination of the clonic spasms in a 

 tonic convulsion, which may or may not be followed by clonic movements. In some 

 fits clonic movements only occur. After large doses a tonic fit may start the series 

 of convulsions, but if the animal recovers from the early fits clonic movements always 

 form part of the convulsion. Still later the animal loses consciousness, and the 

 periodic fits become replaced by continuous clonic movements of the limbs, which only 



