32 THE HUMAN BODY. 



whose business it is to ascertain and communicate to the 

 whole, external changes which occur around it. Since 

 the usefulness of these tissues depends upon the readiness 

 with which slight causes excite them to activity, we may 

 call them the irritable tissues. 



6. Co-ordinating and Automatic Tissues. Such infor- 

 mation as that collected by ministers in foreign parts or by 

 meteorological observers, is usually sent direct to some cen- 

 tral office from which it is redistributed; this mere redis- 

 tribution is, however, in many cases but a small part of the 

 work carried on in such offices. Lotus suppose informa- 

 tion to be obtained that an Indian chief is collecting his 

 men for an attack on some point. The news is probably 

 first transmitted to Washington, and it becomes the duty 

 of the executive officers there to employ certain of the con- 

 stituent units of the nation in such definite work as is 

 needed for its protection. Troops have to be sent to the 

 place threatened; perhaps recruits enlisted; food and 

 clothes, weapons and ammunition must be provided for 

 the army; and so on. In other words, the work of the 

 various classes composing the society has to be organized 

 for the common good; the mere spreading the news 

 of the danger would alone be of little avail. So in the 

 Body: the information forwarded to certain centres from 

 the irritable tissues is used in such a way as to arouse to 

 orderly activity other tissues whose services are required; we 

 find thus in these centres a group of co-ordinating tissues, 

 represented by nerve-cells and possibly by certain other con- 

 stituents of the nerve centres. Certain nerve-cells are also 

 automatic in the physiological sense already pointed out. 

 The highest manifestation of this latter faculty, shown 

 objectively by muscular movements, is subjectively known 

 as the "will," a state of consciousness; and other mental 

 phenomena, as sensations and emotions, are also associated 

 with the activity of nerve-cells lying in the brain. How it 

 is that any one state of a material cell should give rise to a 

 particular state of consciousness is a matter quite beyond 

 our powers of conception; but not really more so than how 

 it is that every portion of matter attracts every other por- 



