514 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
While the diseases of Group 5 are not of importance as causes of 
mortality, they nevertheless exert a certain definite influence which 
we will consider later. 
Directly as well as indirectly these diseases are the cause of im- 
mense economic losses. These affect both the individual and the 
social fabric. The following economic losses may be enumerated: 
(a) Temporary or permanent disablement of the patient as an 
immediate result of the disease, resulting to the individual in tempo- 
rary or permanent loss of earning power, and to society in the loss 
of productive labor; 
(6) Sequelz or complications which permanently impair the indi- 
vidual’s usefulness or hasten death from other causes; 
(c) Expenses of illness, which if due to preventable illness, must 
be regarded as an economic loss; 
(d@) The expense incident to the establishment and maintenance 
of public hospitals, asylums, and charitable agencies to relieve want 
arising from disabling sickness; 
(e) Making vast regions of the earth’s surface uninhabitable for 
the civilized races; while 
(7) Preventable diseases of the domesticated food poisoning ani- 
mals may cause such inroads into their numbers that animal foods 
become scarce and consequently high in price. This is due both to a 
destruction of the animal as well as to a decreased productiveness of 
those surviving. 
With most of the diseases included in the foregoing groups our 
available knowledge is sufficiently adequate to justify us in classify- 
ing them as preventable. Their continued presence with us is chiefly 
due to the lack of ways and means for placing effective control meas- 
ures in operation. It may never be practicable to place in operation 
in civil life the drastic, but nevertheless effective measures which have 
made the military application of preventive medicine so brilliant, 
though the experience with military discipline emphasizes the admin- 
istrative difficulties which are encountered in the civil application of 
these measures, where tact rather than force must win the point. 
Conceiving a population wherein an adequately organized defensive 
and offensive body was available to apply proper measures, we might 
expect that their continued application would have certain effects. 
Among these we may prophesy the following: 
(a) Amn increase in the period of expectation of life, that is 
the probable duration of the life of the hypothetical average in- 
dividual. This change will be accompanied by the following 
phenomena: (1) There will first be a gradual diminution in the 
total death rate, due to the gradual disappearance of the prevent- 
able diseases as causes of mortality. (2) A change in the age dis- 
tribution of the deaths will next be apparent. The majority of 
