Sentence:  The "Cauſe" may be "Want" of <WSD>"Perſpiration</WSD>" : For Much of the Matter of "Haire," in the other "Parts" of the "Body," goeth forth by Inſenſible <WSD>"Perſpiration</WSD>" ; And beſides, the "Skull" being of a more ſolide Subſtance, nouriſheth and aſſimilateth leſſe, and excerneth more. 
Meaning of the word marked with <WSD> tags:  The action or process of perspiring.