STORAGE TISSUES. 31 



servants to put the food into his mouth, had finally to 

 swallow and digest it for himself. Moreover, there is no- 

 logical distinction between a secretory and an excretory 

 cell: each of them is characterized by the formation of cer- 

 tain substances which are poured out on a free surface on 

 the exterior or interior of the Body. Many secretory cells 

 too have no concern with the digestion of food, as for 

 example; those which form the tears and sweat. 



4. Storage Tissue? . The Body does not live from hand 

 to mouth: it has always in health a supply of food materials- 

 accumulated in it beyond its immediate needs. This lies 

 in part in the individual cells themselves, just as in a pros- 

 perous community nearly every one will have some little- 

 pocket-money. But apart from this reserve there are cer- 

 tain cells, a sort of capitalists, which store up considerable- 

 quantities of material and constitute what we will call the- 

 storage tissues. These are especially represented by the- 

 liver-cells and fat-cells, which contain in health a reserve 

 fund for the rest of the Body. Since both of these, to- 

 gether with secretory and excretory cells, are the seats of 

 great chemical activity, they are all often called metabolic 

 tissues. 



5. Irritable Tissues. The maintenance, or at any rate- 

 the best prosperity, of a nation is not fully secured when a 

 division of labor has taken place in food.-supply and food- 

 distribution employments. It is extreniely desirable that 

 means shall be provided by which it may receive informa- 

 tion of external changes which may affect it as a whole, 

 such as the policy of foreign countries ; or which shall en- 

 able the inhabitants of one part to know the needs of an- 

 other, and direct their activity accordingly. Foreign min- 

 isters and consuls and newspaper correspondents are em- 

 ployed to place it in communication with other states and 

 keep it informed as to its interests ; and we find also orga- 

 nizations, such as the meteorological department, to warn 

 distant parts of approaching storms or other climatic 

 changes which may seriously affect the pursuits carried on 

 in them. In the Human Body we have a comparable class 

 of intelligence-gaining tissues lying in the sense organs, 



