434 MEDICAL JURISPRUDENCE
2. Vesicants : Producing blisters. These may "be infected to form
pustules, e.g. cantharis, mylabris wasps ; war gases like lewisite,
mustard gas, etc.
3. Necrotics or Corrosives : Eroding the tissues resulting in
destruction and debris or ulceration, e.g. concentrated mineral
acids and alkalies; creosote, formaldehyde, oxalic acid, phenol,
salicylic acid, etc.
(Note. — In different concentrations some substances can produce either
of these effects externally or internally.)
II. SYSTEMIC POISONS : Substances acting, after being absorbed, at
A. Non-specific or indiscriminate tissue poisons, causing damage to
1. Affecting tissue respiratory enzymes : cyanide ion, etc., e.g.
hydrocyanic acid and cyanides, etc.
2. Affecting enzyme-components, like sulphydril radical (-SH),
e.g. antimony and arsenic preparations (late, systemic effects).
3. Affecting haemoglobin (impeding oxygen transport), e.g. aceta-
nilide, carbon dioxide, carbon monoxide, coal-gas, phenacitin, etc.
4. Affecting general metabolism, e.g. dinitrophenols, thyroid prepa-
B. Specific or Selectively acting poisons :
(Note. — Substances can have toxic actions, simultaneously, on more than
one system, giving a mixed picture.)
1. Neurotropic Poisons: affecting primarily the nervous system.
A. Irritants : Substances causing nervous hyperactivity.
(Note. — On admission the patient is quite likely to be in. a depressed
condition, due to fatigue from over-activity.)
(i) Cerebral (including thalamic) :
(a) Delirients : Mild irritants of the brain producing
excitatory effects short of convulsions, e.g. amphe-
tamine, atropine, belladonna, datura, homatropine,
(b) Convulsants : Producing clonic convulsions, e.g.
absinthe, camphor, cocaine and derivatives, insulia
leptazol, nikethamide, nupercaine, picrotoxine, etc.
(Note. — There are other * apparent ? irritant poisons which,
really * depressants *. These are classified Tinder Depressants
(ii) Spinal : Causing tetanic (tonic)
brucine, nux vomica, strychnine, t^eT^aMe, etc,
(iii) Medullary : Chiefly affecting tfee vomiting centre,
B. Depressants : Decreasing the functional, activity of the
nervous system. "
(i) Cerebral including thalanjic :
(a) Inebrl&nts : Promoting exhifersttion and crafte
hj^peractiviiy due to aft ft infeMtiorL of hitter i