As regards the size of the pupils:
When the pupillary foramina are too small, this constitutes miosis—a condition frequently found in certain serious nervous diseases (locomotor ataxia, paralytic dementia), and in chronic opium poisoning; it is frequent in meningitis. In old persons miosis is a normal condition.
When, on the contrary, the foramina of the pupils are too large, this constitutes mydriasis (poisoning from atropine, intestinal diseases, etc.).
In addition to these, there is anisocoria, when the two foramina are unequal (neurasthenia, chronic alcoholism, first stage of paralytic dementia).
Form of the Pupillary Foramen.—It is not always round, sometimes it is oval (cat's-eye). Frequently the form of the pupil is permanently altered as the result of a surgical operation.
Thus, the contour of the pupil may be broken instead of clear cut; in verifying this phenomenon it is important to inquire whether the subject has suffered from any progressive disease of the iris, such as might produce the same condition.
Anomalies of the Ear.—While in the case of animals the external ear is greatly developed, movable and detached from the cranium, in man it is reduced in size, immovable and attached to the cranium. Two measurements are taken of the ear, the length and the width, and by means of the usual formula we obtain the index of the ear, which for the European race is about 54 per cent. This index has a certain importance because we find that the proportion of width to length steadily increases as we descend through the inferior human races, down to the ape, and the same increase continues if we descend through the different grades of the simian order.
This is to a large extent a result of the fact that, in the descent from man to ape, the lobule of the ear, which is essentially a human form, steadily diminishes, until it finally disappears.
From this it may be concluded that there exist minute zoological differences other than generic between man and animals. As to malformations of the human ear, which may consist of shortness or absence of the lobule (formerly interpreted as a simian inheritance) they are to-day attributed to physiological causes. An abundant circulation produces an ample and fleshy lobe; in oligohæmic constitutions (deficiency of blood) the lobe is delicate, pale and even atrophied. Brachysceles often have a big lobe, and macrosceles, predisposed to phthisis, often have no lobe.
In regard to the external ear we should observe: