24 Trans, Acad. Sci. of St. Louis 
enormously more difficult, of effect. One might call to 
mind the developments in modern medical laboratory 
work accruing chiefly through the application of organic 
chemistry, microscopy and bacteriology—the various 
functional tests and determinations, the extraordinary 
advance in haematology leading to the practical utility 
of blood cultures, transfusion, tests for occult blood in 
_ excreta and diagnostic cytology. Recall, too, the devel- 
opments of thermometry, endoscopy and electro-cardiog- 
raphy and, greatest of all, the X-ray. 
It is curious that it is only in retrospect that we are. 
able to evaluate great advances. The inception of the 
great change is so insignificant and its development so 
gradual that we cannot realize its present or final im- 
port even when the action has acquired great momentum. 
It is searee more than twenty years since Roentgen 
made his epochal discovery. In the early years of its 
medical application its field of utility was considered lim- 
ited to the detection of heavy foreign bodies and the 
study of fractures. Gradually other outlets were found 
for its use until today it has riven diagnostic traditions 
in every branch of clinical medicine. If its growth is 
but a percentage as remarkable in the future ag it has 
been in the past, and personally I cannot believe that 
it will be greater, it will soon come to occupy a position 
of domination—the first of laboratory methods to super- 
sede the supremacy of clinical observation. The only 
thing that has prevented this occurring up to the pres- 
ent is the technical difficulty connected with its use and 
the as yet unsolved problem of educating physicians and 
students in X-ray interpretation—one of the most diff- 
eult arts with which medicine has yet had to deal. 
The mention of certain advances in methods of diag- 
nosis was made in order to present a problem that is 
