378 Proceedings of Royal Society of Edinburgh. [sess. 
The action is, however, of essentially the same nature as the 
morphine action ; the same parts of the central nervous system are 
affected, and in the same way as by morphine, but not in the same 
degree. 
This is what one would expect from chemical considerations, for 
in making these substances no profound change has been effected 
in the morphine molecule, but simply an alkyl radical has been intro- 
duced into one of the outlying groups which compose it. 
II. Acetyl-, diacetyl-, benzoyl-, and dibenzoyl-morphine form a 
group of substances having exactly similar actions. In them one 
or both of the hydroxyl hydrogens of morphine have been replaced 
by an acid radical. 
Comparing them with morphine, their action is the same in kind 
but differs in degree. Their tetanising power is much greater, while 
their narcotic action, although visible after smaller doses, is not nearly 
so profound. Increase of dose, instead of deepening the narcosis, 
brings on tetanus. 
Comparing them with codeine, they induce an equal narcotic 
effect (rabbits) with about one-tenth of the dose, while a dose about 
three times larger is necessary to induce tetanus. Their depressing 
action on motor nerves is about the same. 
It seems quite indifferent which radical is introduced, and whether 
one or both of the hydroxyl hydrogens are replaced. Just as with 
codeine and its analogues, no great change has been made in the 
morphine molecule, but simply in the outlying hydroxyl groups. 
III. In morphine-sulphuric acid and nitroso-morphine the radicals 
HS0 3 and NO replace the hydroxyl hydrogen atoms, and the action 
is modified much in the same w r ay as by the introduction of other 
acid radicals (II.). 
IV. Chlorocodide and Trichloromorphide are chlorine derivatives ; 
in the former Cl replaces the OH of codeine, while in the latter both 
hydroxyl groups, and in addition one H atom of morphine, have been 
replaced by 3 Cl. 
They retain the characteristic actions of morphine on the nervous 
system, but are in addition marked muscle poisons. 
V. In metho-codeine two methyl molecules have been introduced 
into morphine, one of which replaces a hydroxyl hydrogen atom, 
while the other replaces an H in the body of the morphine molecule. 
