Sentence:  From the left chamber or "ventricle" of the strong muscular mass, the "heart", a large tube arises, called the "aorta"; and by a continued division or <WSD>ramification</WSD>, opens a way for the bright scarlet blood to the very minutest part of the living frame ... 
Meaning of the word marked with <WSD> tags:  A branching-out, the act or result of developing branches; specifically the divergence of the stem and limbs of a plant into smaller ones, or of similar developments in blood vessels, anatomical structures etc.