324 Proceedings of Royal Society of Edinburgh. [sess. 
analogy that several of the other alkaloids are known to be pyri- 
dine or chinoline derivatives, one is inclined to regard morphine as 
of the same class until conclusive proof is advanced to the contrary. 
Physiological Action of Morphine. 
There is now complete agreement among authors regarding the 
general symptoms observed after the administration of morphine, 
although many points of practical, as well as theoretical, interest still 
require elucidation. All recent observers state that the central 
nervous system is the part primarily affected, and have described 
the symptoms as divisible into two stages — a narcotic and a 
tetanic. 
Frogs . — After 2-5 centigrams of a soluble salt of morphine have 
been given subcutaneously to a frog, the animal becomes in a few 
minutes dull and heavy, and shows a distinct inclination to remain 
quietly in one position. When pinched or otherwise irritated, it at 
first jumps quite well, but very shortly loses its power of accurate 
muscular co-ordination. It then ceases to move away even when 
pinched, and if placed on its back remains in that position. 
The corneal reflex becomes abolished, while the spinal reflexes are 
diminished, but seldom wholly disappear. All these symptoms 
indicate depression of the brain and spinal cord, and Witkowski has 
pointed out that the cerebral lobes succumb first, the other parts 
of the central nervous system becoming involved in order from 
before backwards. 
The frog remains in this helpless narcotised condition for a 
varying time until the second stage supervenes, the spinal reflexes 
gradually becoming more and more exaggerated until tetanic spasms 
occur spontaneously and on stimulation. After a longer or shorter 
period exhaustion ensues, the frog then responding to stimulation 
by a mere twitch. It may finally die or gradually recover. 
During both stages the brain is deeply narcotised, as irritation of 
the cornea during the tetanic condition brings on a general spasm 
but no closure of the eyelid. The spasms are spinal, as section of 
the cord at the atlanto-occipital membrane does not stop them ; the 
succeeding exhaustion also arises from the spinal cord, as the motor 
nerves and muscles are found to be only slightly diminished in 
electric irritability. A very distinct peculiarity of the morphine 
