Immigrant Fridays turned into Saturday.  I wrote too soon when I promised regular theme days.  The semester started and, as always, hijacked my life.
Toward the end of the 19th Century, examinations of immigrants began at places like Ellis Island.  To this day, immigrants with certain diseases like syphilis, tuberculosis, and HIV/AIDS [the last one until 2010 when Obama got rid of it--thanks Ben!] are barred from legal residency.  Back in the day, insanity and idiocy were also on the list ("insanity" differently defined is on the list now too) and I  often wondered how officials determined the two.  I found a  1903 volume titled Book of instructions for the medical inspection of immigrants by  the U.S. Public Health Service ("Prepared by Direction of the  Surgeon-General"), which answered my questions not at all, but was  entertaining enough especially since it contains a reference to "ignorant representatives of emotional races." This last one goes unexplained so I guess everyone knew who they were talking about. 
Here are some of the instructions:
The medical examination should be made by daylight and never, except in  an emergency, attempted in poorly lighted rooms or by artificial light.  The preliminary line inspection should be conducted on an even, level  surface, so that the passengers may not be tempted to look where they  are stepping. ... Care should be taken to prevent  crowding, to maintain a single file evenly spaced, with the individuals  well separated (10 feet).
Good to know about the lighting.  You can't see crazy in the dark. 
Below are two of the document's subdivisions.  One on insanity and the other on "idiots."  Both of them  pose ethical issues today, but how in the world did they determine these at the turn of the century (daylight  notwithstanding)?  How could English-speaking officials, with few if any translators, keep an ear out for illusions or hallucinations?
Subdivision III.—Insane persons. 
The following definition of insanity may be  accepted for guidance: Insanity is a deranged and abnormal condition of  the mental faculties, accompanied by delusions or hallucinations or  illusions, or manifesting itself in homicidal or suicidal tendencies or  persistent mental depression, or inability to distinguish between right  and wrong.
In the case of immigrants, particularly the ignorant representatives of emotional races [!!!], due allowance should be made for temporary demonstrations  of excitement, fear, or grief, and reliance chiefly placed upon  absolute assurance of the existence of delusions or persistent refusal  to talk or continued abstinence from eating.
Persons suffering from acute attacks of delirium  tremens should be certified as insane. Those presenting less active  evidence of alcoholism should be regarded as coming under the heading of  likely to become public charges, as should also all cases of simple  epilepsy or hysteria.
At least two officers  should concur in a certificate of insanity, and when this is  impracticable the medical officer should recommend the employment of a  local physician in good standing, and they shall jointly sign the  certificate.
The evidence on which a certificate of insanity is  based should be made a matter of permanent record. It should always  include, among other things, the physical appearance, character of  hallucinations, delusions, or illusions, and a brief history of the  peculiarities noted while the case was under observation.
Subdivision IV.—Idiots. 
The following definition of an idiot may be accepted for guidance:
An idiot is a person  exhibiting such a degree of mental defect, either inherited or developed  during the early period of life, as incapacitates the individual for  self-maintenance or ability to properly care for himself or his  interests. (Richardson.)
Idiocy is a defect of mind which is either  congenital or due to causes operating during the first few years of  life, before there has been a development of the mental faculties, and  may exist in different degrees. (Standard Dictionary, by Maudslev;  Responsibility in Mental Diseases, chapter 3, p. 66.) 
In case of persons of  impaired mentality to whom the term " idiot" or " insane," as above  defined, is inapplicable, certificates should be made in such terms as  may be deemed best calculated to convey an idea of the degree of  disability in each particular case.