CELLS AND TISSUES 



49. An Ordinary Animal is a Community or Colony of 

 Cells. An animal such as a horse or a man, made up of 

 millions of cells, may be compared to a colony 

 or community of one-celled animals. When 

 a child is born in a community of people, we 

 cannot tell what part in the 

 community it is destined to fill. 

 When a new cell is formed in 

 the body, by the division of an 

 old cell into two cells, it may 

 serve its community as a rail- 

 road man serves a community 

 of people, that is, as a red blood 

 cell, and carry food from place 

 to place ; or it may be a farmer 

 cell, that is, a digestive cell, and 

 convert crude material into sub- 

 stances ready for use by the 

 other cells. It may be a senti- 

 nel and soldier, that is, a white 

 blood cell, and go to any place 

 that is attacked by foreign or- 

 ganisms, such as microbes, or it 

 may help to repair a break in the 

 wall, as when the white blood 

 cells (a kind of "jack at all 

 FIG QO The trades") collect in great numbers 



FlG 3I _ 

 undergoing Di- 



Ameba (as anc j form the white matter seen 



seen under a 



the pro- 

 cess are shown. 

 The nucleus di- 

 vides as well as the 

 rest of the cell. The 



, < . i r\ i rest 01 iiicL.cn. xiic 



high power of around a cut in the flesh, or a mother cell divides 

 the micro- sore t h a t is healing. It may be in ' two dau s hter 



scope) taking / cells. 



food. a carpenter cell, that is, a bone 



cell, and help to form the framework or skeleton of the 

 great house which shelters the community ; and last of 

 all, it may be a director and guide for^the community, 

 that is, one of the nerve cells, which correspond to the 



