THE PHARMACOLOGICAL ACTION OF TUTU. 315 



ments can be obtained when the brain is divided below the pons, but they are less 

 characteristic and are more difficult to induce than when the pons is intact. In frogs 

 the optic lobes seem to be the most important centres affected. Unequivocal convulsive 

 movements were not obtained below a section of the spinal cord (see, however, note 

 below). 



3. The convulsions arising in the pons are very susceptible to anaesthetics. This 

 probably explains why convulsions are limited to one side after excision of one cerebral 

 hemisphere during the continuance of the anaesthesia. 



4. In unansesthetised rabbits the two fore limbs act together, and the two hind 

 limbs act in concert and synchronously during tutin convulsions ; in the anaesthetised 

 animal the limb movements are often asynchronous. Individual muscles of the limbs 

 often act vicariously, and this probably explains the irregular clonus which the move- 

 ments of the limbs show. 



5. Preceding the onset of the convulsions the medullary centres are stimulated. 

 This effect is also produced by non-convulsant doses. 



6. All doses which produce an obvious action cause in rabbits a fall of body 

 temperature. 



7. When heated with dilute caustic alkali solutions, tutin rapidly decomposes, the 

 product being pharmacologically inactive. Prolonged heating with dilute acids leads 

 to the same result. 



8. The substance most closely allied to tutin, namely coriamyrtin, is a more 

 powerful convulsant, and, for similar physiological doses, is more rapid and more 

 transient in action than tutin. 



Note. — Since the preceding paper was accepted for publication a research on the Physiological Action 

 of Tutin by Fitchett and Malcolm has appeared in the Quarterly Journal of Experimental Physiology 

 (vol. ii. p. 335; Oct. 1909); an extended description of the research, with protocols, being given by 

 Fitchett in the Transactions of the New Zealand Institute (vol. xli. p. 286). The effect of tutin on 

 various classes of animals is described, and, in so far as our experiments are common, our results are in 

 general agreement. On a few physiological points we are not in accord. Fitchett and Malcolm have 

 apparently not obtained any evidence of stimulation of the cardio-inhibitory centre, but they appear to have 

 investigated the matter only in animals under anaesthetics. As I have shown, no decided stimulation of this 

 centre occurs during surgical ansesthesia. 



They also attribute to the motor area a smaller and to the spinal cord a larger share in the production of 

 the convulsions than I have done. They state that after inducing convulsions in a cat under chloroform 

 by a large dose of tutin injected hypodermically and removing the right cerebral hemisphere, "the con- 

 vulsions continued just as before, affecting both sides equally," and after scooping out the left cerebral 

 hemisphere "the convulsions seemed to be quite unaffected." "The spinal cord was then divided in the 

 mid-dorsal region. The movements below the level of section were absent or abolished at first, but four 

 minutes after the section clonic and tonic spasms of the hind limbs were observed, and these continued 

 intermittently until death ensued, a quarter of an hour later." The continuance of the convulsions after 

 removal of the cerebral hemispheres is explained by the fact that, according to the protocol of the experiment 

 (No. 152 in Fitchett's paper, p. 356), the anaesthetic was stopped when the tutin was administered — twenty- 

 two minutes before the appearance of any symptoms. The only difference in our results is the effect 

 obtained behind a transection of the spinal cord. All my transection experiments were made on rabbits, 



TRANS. ROY. SOC. EDIN., VOL. XLVII. PART II. (NO. 13). 48 



