Sentence:  There is a bond of union, then, between the living organisms of animals and plants; but how the physiorganic forces of attraction and repulsion merge into the physioinstinctual forces of sensation, and these again into the emotional forces of attraction and repulsion, we cannot possibly determine ; and we are still more blind, if possible, with regard to the connection of the <WSD>physiomental</WSD> forces of human understanding and intelligence, with all the other kinds of forces. 
Meaning of the word marked with <WSD> tags:  Pertaining to the biological determinants of emotion or cognition.