CHAPTER XVI. 



THE AUTOGENOUS DISEASES. 



All living things are composed of cells. The simplest forms of 

 life are unicellular, and in these all the functions of life devolve upon 

 the single cell ; absorption, secretion, and excretion must be carried 

 on by the same cell. A collection of unicellular organisms may be 

 compared to a community of men with every individual his own 

 tailor, shoemaker, carpenter, cook, farmer, gardener, blacksmith, etc. 

 Nevertheless it is true that in communities of unicellular organisms 

 the accumulation of their own secretions and excretions impair the 

 growth of the individual and finally rob it of its life. But only the 

 lowest forms of life are unicellular ; all others are multicellular. In 

 the higher animals there is a differentiation not only in the size and 

 structure of the cells, but in the duties imposed upon them. The 

 body of man may be compared to a community in which labor has 

 been specialized. Certain groups of cells, which we designate by 

 the term "organ," take upon themselves the task of doing some 

 special line of work, the well doing of which is essential to the life, 

 not only of that group, but of other groups as well, or of the body 

 as a whole. There is an interdependence among the various organs. 

 Certain groups of cells supply the fluids or juices which act as digest- 

 ants, and among these there is again a division of labor. The sal- 

 ivary glands supply a fluid which partially digests the starch of our 

 food ; the peptic glands supply the gastric juice which does the pre- 

 liminary work in digestion of the proteids, while the pancreatic juice 

 completes the digestion of the starches, begun in the mouth, of the 

 proteids begun in the stomach, and does the special work of emulsi- 

 fying fats. Harm results to the individual when any part of the 

 digestive processes is not properly carried on, and even some of the 

 products of complete digestion are harmful when permitted to enter 

 the circulation unchanged. The peptons must be converted in part at 

 least into serum albumin by the absorbing mechanism of the walls 

 of the intestines, and while ten per cent, of the fat of the food is 

 split up into glycerin and fatty acids by the action of the pancreatic 

 juice, a much smaller per cent, enters the thoracic duct in this divided 

 form. The food taken may be proper both in quality and in quan- 

 tity and the digestive juices may do their work promptly and satis- 

 factorily, but if the absorbents fail to perform their functions properly, 

 disease results. Again it may happen that the failure lies in im- 

 proper or imperfect assimilation, and the result becomes equally dis- 



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