710 POISONS : THEIR EFFECTS AND DETECTION. [§§ 909-9II. 
Guinea-pigs.—In guinea-pigs there were dulness and stupefaction, 
with some weakness of the hind limbs. 
Rats.—The symptoms in rats were almost entirely nervous ; they 
became drowsy and apathetic, and there was paralysis of the hind legs. 
Rabbits,—In rabbits, also, the symptoms were mainly those caused 
by an affection of the nervous system. There was paralysis, which 
affected either the hind legs only, or all four limbs. The cervical 
muscles became so weak that the animal was unable to hold its head up. 
Diarrhoea occurred and persisted until death. If the dose is not large 
enough to kill rapidly, the reflex irritability is decidedly increased, so 
that the slightest excitation may cause the animal to cower and tremble 
all over. Now appear twitchings and contractions of single groups of 
muscles, and this excitement becomes general. The respirations also 
become slower and more difficult, and sometimes there is well-marked 
dilatation of the vessels of the ears and fundi oculi. Convulsions close 
the scene. 
§ 909. Circulation.—The effect of the salt on the frog’s heart was 
also studied in detail. It seems that, under the influence of a soluble 
salt of nickel, the heart beats more and more slowly, it becomes smaller 
and paler, and does not contract evenly throughout the whole extent of 
the ventricle ; but the rhythm of the ventricular and auricular con¬ 
tractions is never lost. 
It is probable that there is a vaso-motor paralysis of the abdominal 
vessels ; the blood-pressure falls, and the heart is not stimulated by the 
blood itself as in its normal state. In support of this view, it is found 
that, by either pressing on the abdomen or simply inverting the frog, 
the heart swells up, fills with blood, and for a time beats well. 
Nervous System.—The toxic action is referable to the central 
nervous system, and not to that of peripheral motor nerve-endings or 
motor nerve-fibres. It is probable that both nickel and cobalt paralyse 
to some extent the cerebrum. The action on the nerve-centres is similar 
to that of platinum or barium, and quite different from that of iron. 
§ 910. Action on Striped Muscle.—Neither nickel nor cobalt has 
any effect on striped muscle. In this they both differ from arsenic, 
antimony, mercury, lead, and iron—all of which, in large doses, diminish 
the work which healthy muscle is capable of performing. 
§ 911. Separation of Nickel or Cobalt from the Organic Matters 
or Tissues.—It is very necessary, if any case of poisoning should occur 
by either or both of these metals, to destroy completely the organic 
matters. Both nickel and cobalt are thrown down, if in the form of 
acetate, from a neutral solution by sulphuretted hydrogen ; but the 
precipitation does not take place in the presence of free mineral acid ; 
lienee, in the routine process of analysis, sulphuretted hydrogen is 
passed into the acid liquid, and any precipitate filtered off. The liquid 
