26 PROFESSOR C. R. MARSHALL ON THE 



blood. If the injection is made much more slowly, greater or less retardation and 

 shallowness, but not actual stoppage, of the respiration may be produced. If larger 

 doses are employed and rapidly injected, the respiration is quickly and completely 

 paralysed, and it usually fails to restart spontaneously ; or, if it does commence again, 

 it remains inefficient. In such cases artificial respiration is generally able to reinstate 

 the respiration unless the dose administered has been excessive. 



Effect on Decerebrate Animals. — On decerebrate animals, if time has been allowed 

 for the influence of the angesthetic to pass away, the effect of tetra-methyl-ammonium 

 chloride on the respiration is, in some respects, different from that described as 

 occurring in anaesthetised animals. In the latter no preliminary stimulation of the 

 respiration, beyond a slight increase in depth of one or two respirations, occurs with 

 any dose of the drug ; in the former this effect is a common feature of its action. And 

 not only may there be the appearance of stimulation before the paralysis occurs, but 

 also the recovery from the paralysis is quicker and is often accompanied by greater 

 respiratory activity. Further, in some decerebrate animals the quantity of tetra- 

 methyl-ammonium chloride necessary to cause respiratory paralysis has been several 

 times that required for anaesthetised animals ; and in these animals especially the 

 stimulant effect on the respiration has been very marked. If, however, the decerebrate 

 animal is lightly anaesthetised, the effects are similar to those seen in anaesthetised but 

 otherwise normal animals. 



The stimulating effect on the respiration of a decerebrate animal of a dose of tetra- 

 methyl-ammonium chloride usually sufficient to paralyse the respiration of an anaes- 

 thetised animal, and the paralysing effect of a large dose, are shown in fig. 7. The 

 animal, a rabbit (2450 g.), was anaesthetised with ether containing a little chloroform. 

 At 11.3 the brain above the corpora quadrigemina was removed, and between 11.10 

 and 11.20 the fifth cranial nerves were cut proximal to the Gasserian ganglia. The 

 anaesthetic was then stopped. At 11.36, 0*6 mg. tetra-methyl-ammonium chloride 

 was injected into the right facial vein, with much the same result as is shown in the 

 first part of the figure. At 11.44^, 1 mg. was injected, and, as is seen, the respiration 

 was powerfully stimulated. No depression or paralysis occurred. At 11.58 the same 

 dose was injected more slowly, and a similar but less marked effect resulted. Before 

 the effects of this dose had passed away, 2 mg. was injected, and further transient 

 stimulation followed by temporary paralysis obtained. Subsequently 5 mg. was injected, 

 with the result shown in the second part of the figure. Occasional shallow respiratory 

 movements occurred later, but the respiration failed to re-establish itself and the 

 animal succumbed. 



As the effects obtained on decerebrate animals were slightly variable, and as the 

 matter is of some importance for the purposes of this paper, a summary of twelve 

 experiments made on rabbits is given. The animals were anaesthetised with ether, and 

 the anaesthesia maintained with a mixture of ether and chloroform until the mid-brain 

 was divided and the cerebrum removed. In some experiments the fifth cranial nerves 



