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196 IOWA ACADEMY OF SCIENCE 
live tissue type. The character of the rather superficial circumscribed yellow- 
ish elevations so commonly observed in infectious cases, correspond very well 
with the changes produced experimentally by treating animals with such sub- 
stances as adrenalin, nicotine, bacteria and their toxins, et cetera, and I am by 
no means convinced that they bear any relationship to the type of sclerosis 
here discussed. 
The degenerative changes which occur in advanced cases are invariably of 
a secondary character and almost always begin in the deeper layer of the 
intima. One of the early changes observed in the smaller vessels is a fission 
or lamellation of the elastica interna, the interstices becoming filled with con- 
nective tissue cells. 
