eye
under examination is exactly in the centre, and looks directly at the
middle point of the semicircle, corresponding to 0 in the scale: the
testing object, a small ball, is passed backwards or forwards along the
semicircle. A graduated scale, placed on the semicircle, marks the point
limiting the field of vision, and the result is registered on a diagram.
The average limit of the normal field of vision is 90 mm. on the
temporal side, 55 mm. on the nasal side, 55 mm. above and 60 mm. below
(see Fig. 42). If a suitable instrument is not available, a series of
concentric circles may be traced on a slate and the patient placed at a
certain distance with one eye covered. The examiner then touches the
different points of the circles with his hand and asks the patient
whether he can see it when his eye is fixed on the central point. In
this way the various points limiting the field of vision are noted and
furnish, when united, the boundary line.

=FIG. 37
Diagram Showing Normal Vision=

_Hearing_ is generally less acute in the criminal than in the normal
individual, but does not show special anomalies. It may be tested by
speaking in a low voice at a certain distance from the patient, or by
holding an ordinary watch a little way from his ear.

_Smell._ Olfactory acuteness is tested by solutions of essences of
varying strength, which the patient should be requested to place in
order, indicating the one in which he first detects an odour. Ottolenghi
has invented a graduated osmometer which is easy to use. The criminal
generally shows olfactory obtuseness.

_Taste_ is tested in the same way as smell, by varying solutions of
saccharine or strychnine dropped on to the patient's tongue by means of
a special medicine dropper. The mouth should be rinsed out each time.
Normal persons taste the bitterness of sulphate of strychnine in a
solution 1:600,000; the sweetness of saccharine in a solution 1:100,000.
The sense of taste is less acute in criminaloids than in normal persons,
and is specially obtuse in born criminals, 33% of whom show complete
obtuseness.

_Movements._ Normal individuals in a state of repose remain almost
motionless, and their gestures are always appropriate. Lunatics and
imbeciles have a habit of speaking and gesticulating even when they are
not interrogated. Nervous diseases manifest themselves in facial
contortions or slight spasmodic contractions. In melancholia and all
forms of depression, the