190 
ROBERT FORMAL). 
beast, must bear in mind that there are benign and malignant 
tumors, and that the recidivety would greatly influence his prog¬ 
nosis, even if he cannot recall the exact microscopical picture. 
When we want to treat disease it is essential to observe and 
know not only the symptoms and peculiarity, but also the name 
of the disease to which the symptoms belong, and when we 
wish to remove a tumor we must remember the kinds of tumors 
that pathology teaches. Tumors are studied under the heading 
of complete morbid processes, termed pseudo formations, leading 
to the development of useless tissue in contrast to regeneration, 
the term new tissue formation. 
Definition —(a) Clinical: A tumor is a swelling developed 
without the symptom of inflammation ; it is permanent and has 
a tendency to stay and increase in size, (b) Anatomical: A 
tumor is a multiplication of preexisting tissue above physiolog¬ 
ical limits, abnormal as to space and tissue. 
Synonyms : Hyperplasis, swelling, neoformation, neoplasm. 
Inflammation neoformation may resemble tumors to such an 
extent as to make the distinction an exceedingly difficult one, 
even on morphological and physiological bases. Tumors origi¬ 
nate spontaneously, but do not disappear so, while inflamma¬ 
tory neoformations do not appear spontaneously, but may dis¬ 
appear so. 
Pathogenesis of Tumors.—Numerous theories have been ad¬ 
vanced from time to time to explain the causes of tumors, but 
up to the present day our theories have been hypotheses failing 
to explain the causation of tumors. 
1. Dyscrasia or diathesis, theory advanced by Billroth and 
older writers, described formation of tumors to a diseased state 
of the fluids of the body and an inherited peculiarity ; if this be 
true, however, the question naturally would arise, when did the 
first tumor start, and if Adam was created with the first tumor it 
is strange that a tumory nation had not been developed. 
2. The mechanical or inflammatory theory comes next in ex¬ 
istence and ascribes the formation of tumors due to irritants— 
e. g., epitheliomia in pipe smokers, and to injuries. Clinical 
