258 THE HUMAN SKIN : 



Instead of consisting of one single cell they consist of several cells 

 joined together into a little colony, more complexly arranged as 

 we get higher in the scale. They become, in fact, multicellular, or 

 many-celled organisms. I can best compare the difference in the 

 two conditions by a familiar simile. 



Imagine for a moment a small primitive country village, such 

 as we still happily find in Derbyshire, in which a small tradesman 

 keeps the little shop, for it is usually the only one, where he sells 

 everything — meat occasionally, boots, groceries, peg-tops, hats, 

 stockings, black-lead, and postage stamps. He is his own sales- 

 man, takes the money himself, buys in his own stores in the 

 neighbouring town, puts up his own shutters, and sweeps out his 

 own shop. He does, in fact, everything himself, but it is, neces- 

 sarily, in a very small way. There you have a unicellular structure, 

 a very primitive arrangement, such as the lowly Amoeba, per- 

 fectly fulfilling all the village requirements. Let us imagine, 

 however, that years afterwards, owing to some cause or other, such 

 as the discovery of coal in the district where our village stood, it 

 has grown up into a large and populous town; railways, telegraphs, 

 and telephones, the later discoveries of science, have made the 

 little village shop quite inadequate for the demands of the inhabit- 

 ants, and, on its former site, there stands an immense Great 

 Northern Supply Stores, with hundreds of assistants employed in 

 its work. One group of them now looks after the meat depart- 

 ment, another the boot department, and so on ; whilst a special 

 set of cashiers takes the money, and others have as their duty to 

 sweep out the Stores, and put up the shutters ; the whole of them 

 being under the governance of the Directors of the Company. 

 There you have a picture of a multicellular shop ; a complex 

 organism, such as the human body, where the myriads of little 

 cells are divided into groups, each of which groups has some 

 special functions to perform with relation to the harmonious working 

 of the whole, and all of which are under the direct control and 

 supervision of the Directors, viz.^ in this case, the Central Nervous 

 system. 



In the human body, then, the cells can be broadly divided into 

 groups, each of which has its own particular structure and function, 

 or functions, and each of these groups is called a Tissue. Thus 



