Sentence:  The importance of knowing in what chemical forms the hormone may exist is accentuated by the recent observation that there exists an abnormally long-acting TSH in <WSD>blood</WSD> drawn from many thyrotoxic patients ( Adams , 1958 ) . 
Meaning of the word marked with <WSD> tags:  the fluid (red in vertebrates) that is pumped through the body by the heart and contains plasma, blood cells, and platelets