98 THE DATA OF BIOLOGY. 



sive fluid correspond with some external danger which may 

 never occur? or again: — How can the dynamical phenomena 

 constituting perception correspond with the statical phe- 

 nomena of the solid body perceived? The only reply is, 

 that we have no word sufficiently general to comprehend all 

 forms of this relation between the organism and its medium, 

 and yet sufficiently specific to convey an adequate idea of 

 the relation; and that the word correspondence seems the 

 least objectionable. The fact to be expressed in all cases is 

 that certain changes, continuous or discontinuous, in the 

 organism, are connected after such a manner that in their 

 amounts, or variations, or periods of occurrence, or modes of 

 succession, they have a reference to external actions, constant 

 or serial, actual or potential — a reference such that a definite 

 relation among any members of the one group, implies a 

 definite relation among certain members of the other group. 



§ 30. The presentation of the phenomena under this gen- 

 eral form, suggests that our conception of Life may be reduced 

 to its most abstract shape by regarding its elements as relations 

 only. If a creature's rate of assimilation is increased in con- 

 sequence of a decrease of temperature in the environment, it 

 is that the relation between the food consumed and the heat 

 produced, is so re-adjusted by multiplying both its members, 

 that the altered relation in the environment between the 

 quantity of heat absorbed from, and radiated to, bodies of a 

 given temperature, is counterbalanced. If a sound or a scent 

 wafted to it on the breeze prompts the stag to dart away 

 from the deer-stalker, it is that there exists in its neighbour- 

 hood a relation between a certain sensible property and cer- 

 tain actions dangerous to the stag, while in its body there 

 exists an adapted relation between the impression this sensi- 

 ble property produces, and the actions by which danger may 

 be escaped. If inquiry has led the chemist to a law, enabling 

 him to tell how much of any one element will combine with 

 so much of another, it is that there has been established in 



