Sentence:  We may pass by a large number of truly mental phenomena as not being necessarily attended with consciousness, and in these the relation of the transformation of Energy, or the doing of work, is probably the same as obtains in ordinary vital or metabolic action, viz., the <WSD>ingo</WSD> of force through stimuli and pabulum exactly balances the outgo in the form of heat, mechanical movement, and the potential energy still remaining in the living matter, or its products, while nothing is counted for the peculiar properties given by the state of organism. 
Meaning of the word marked with <WSD> tags:  The act or process of going in.