THE BEGINNINGS OF LIFE. 109 



vegetable kingdom. In man we find a fully developed 

 and almost inconceivably complex organism; in the 

 working of which, as in that of any ordinary but ex- 

 tremely complex piece of machinery, there is seen to 

 be the closest interdependence between the actions of 

 the several parts. Destined as a whole to perform 

 a certain work, we may constantly see, for instance, 

 in the wool-factories of our manufacturing districts 

 a piece of machinery in which the sum total of work 

 to be done is parcelled out amongst different re- 

 lated and interdependent parts wheels of every de- 

 scription, large and small, plain and toothed ; combs of 

 various kinds; rhythmically acting knives, reels and 

 thread twisters, all combine simultaneously or suc- 

 cessively to elaborate the woof out of which our gar- 

 ments are woven. The action of some parts are 

 more essential, that of others less essential to the 

 action of the machine as a whole. An interference 

 with the revolution of some central wheel may suffice 

 instantly to interrupt the working of the entire mechan- 

 ism, just as the functional workings in the body of 

 a highly organized vertebrate animal may be as sud- 

 denly arrested by a puncture in a particular part of its 

 nervous system. In both instances the first result is 

 a simple cessation in the action of a complex machine ; 

 and, in the case of the animal seeing that its body 

 has been gradually built up in a given manner under 

 the influence of certain definite actions or functions, 

 the continuance of which is absolutely necessary it 



