i879-] 
A iner lean Nervousness. 
599 
precedent in the history of mankind. The ancients had no 
nervous disease, or almost none, save a few cases of insanity 
and epilepsy here and there ; and our moderns knew little or 
nothing about them until the present century. 
The scientific proofs of this unprecedented nervousness of 
the Americans during this generation are very numerous. 
First of all, there is the increased sensitiveness to cold and 
heat which is observed among all our brain-working classes. 
Our fathers were content with a temperature of 6o° F. We 
must have, to be comfortable, a temperature of at least 70° ; 
and there are many families who keep their rooms at even a 
much higher temperature. In other words, we are 10 degrees 
more sensitive to cold than were our fathers. The heat of 
our summers is no greater than it was a century ago, but 
the cases of sunstroke and heat prostration are widely out of 
proportion to the increase in our population. 
One of the very best signs of our civilisation is found in 
the premature decay of our teeth. Special explanations 
without number have been offered for this long-observed 
phenomenon — such as the use of sweets, the use of acids, 
negleCt of cleanliness, and the use of food that requires little 
mastication. But they who urge these special faCts to 
account for the decay of teeth of our civilisation would, by 
proper inquiry, learn that the savages and negroes, and semi- 
barbarians everywhere, in many cases use sweets far more 
than we, and never clean their mouths, and never suffer, 
except in old age, from cavities in the teeth. The cause of 
the decay of teeth is subjective far more than objective, in 
the constitution of the modern civilised man. Similarly, 
also, with regard to irregularities of the teeth, which, as is 
now known, are dependent on bad nutrition of the jaws. 
Delicacy of digestion is one of the best known and first 
observed effects of civilisation upon the nervous system. In 
all the great cities of the East, among the brain-working 
classes of our large cities everywhere, pork in all its varieties 
and preparations has taken a subordinate place among the 
meats upon our tables, for the reason that the stomach of 
the brain-worker cannot digest it. Three times a day, and 
every day in the year almost, pork in some form was the 
only dependence of our fathers in the last generation, who 
could eat it freely without ever asking themselves whether it 
was easy or hard to be digested. 
The eyes, also, are good barometers of our nervous civili- 
sation. The increase of sesthenopia and shortsightedness, 
and, in general, of the functional disorders of the eye, are 
demonstrated faCts, and are most instructive. The great 
