RELATIONS. 151 



comes it to pass that the foetus lives, and grows, and thrives 

 without it ? The answer is, that the blood of the foetus 

 is the mother's , that it has undergone that action in her 

 habit; that one pair of lungs serves for both. When the 

 animals are separated, a new necessity arises ; and to meet 

 this necessity as soon as it occurs, an organization is pre- 

 pared. It is ready for its purpose ; it only waits for the 

 atmosphere ; it^begins to play, the moment the air is admit- 

 ted to it. 



CHAP. XV. 



RELATIONS. 



When several different parts contribute to one effect ; 

 or, which is the same thing, when an effect is produced by 

 the joint action of different instruments; the fitness of such 

 parts or instruments to one another, for the purpose of pro- 

 ducing, by their united action, the effect, is what I call re- 

 lation ; and wherever this is observed in the works of na- 

 ture or of man, it appears to me to carry along with it de- 

 cisive evidence of understanding, intention, art. In ex- 

 amining, for instance, the several parts of a ivatch, the 

 spring, the barrel, the chain, the fusee, the balance, the 

 wheels of various sizes, forms and positions, what is it 

 which would take the observer's attention, as most plainly 

 evincing a construction, directed, by thought, deliberation, 

 and contrivance? It is the suitableness of these parts to 

 one another, first, in the succession and order in which 

 they act; and, secondly, with a view to the effect finally 

 produced. Thus, referring the spring to the wheels, he 

 sees in it, that which originates and upholds their mo- 

 tion ; in the chain, that which transmits the motion to the 

 fusee ; in the fusee, that which communicates it to the 

 wheels; in the conical figure of the fusee, if he refer back 

 again to the spring, he sees that which corrects the ine- 

 quality of its force. Referring the wheels to one another, 

 he notices, first, their teeth, which would have been without 

 use or meaning, if there had been only one wheel, or if the 

 wheels had had no connexion between themselves, or com- 

 mon bearing upon some joint effect; secondly, the corres- 

 pondency of their position, so that the teeth of one wheel 

 eatch into the teeth of another ; thirdly, the proportion ob- 

 served in the number of teeth of each wheel, which de- 



