559 
of Edinburgh, Session 1868-69. 
action of atropia on the pupil. The experiments were made with 
the hydrochlorate of tropia and with soda salts of each of the 
acids. Although, however, tropia differs so strikingly from atropia 
in being quite unable to influence the pupil, it resembles it in 
some of its other physiological effects. Like atropia, it is a power- 
ful paralysing agent, and it produces paralysis in very much the 
same way as atropia does. In virtue of this action, tropia is an 
active poison. 
Apart from the immediate object of these researches, some 
interest is attached to this portion of the investigation on account 
of its bearing on practical therapeutics. It has been shown by 
Professor G-arrod, that when small quantities of caustic potash or 
soda are added to solutions of hyoscyamus, stramonium, belladonna, 
or atropia, the activity of these substances appears to be destroyed.* 
More recently, Dr John Harley, of London, has pointed out that 
the same effect is produced by caustic lime and by ammonia.f 
This conclusion was arrived at, principally, by observing that the 
pupil was not affected by preparations to which they had pre- 
viously added one or other of these alkalies. The decomposition 
effected by potash, soda, lime, and ammonia, is the same as that 
which the authors have described; and by an examination of the 
separate products of this decomposition they are enabled to confirm 
the observation of Drs G-arrod and Harley, and to add to it the 
additional fact that the products of this decomposition are not 
altogether inert. 
The last portion of this paper, to which the authors think it 
advisable to draw attention, is that in which they describe some 
experiments with the salts of methyl- and of ethyl-strychnium, 
which were performed subsequently to their first communication. 
These additional experiments were made with the view to establish 
beyond the possibility of doubt, the truth of their statement,, that 
these substances act as simple paralysers of motor nerves. In a 
paper recently communicated to the French Academy of Sciences, 
two able observers, Messrs Jolyet and Cahours, have confirmed the 
result that these substances possess an action analogous to that of 
wourali (curara); but they have, besides, observed symptoms which 
* Medico-Cliirurgical Transactions, vol. xli. 1858, p. 58. 
f The Old Vegetable Neurotics, I860, p. 211. 
4 D 
VOL. VI. 
