114 NUTRITIONAL PHYSIOLOGY 



the surroundings are normal, as is presumably the case 

 within the vessels, they keep their integrity, or at least do 

 not disintegrate en masse. When they are brought in con- 

 tact with foreign surfaces they do undergo prompt decom- 

 position and, of course, their constituent material is dis- 

 solved in the plasma. Something derived from the blood- 

 plates sets in motion the series of chemical reactions which 

 leads at last to the perfecting of an enzyme, thrombin, 



Fig. 16. The origin of the lymphatics. This is an extension 

 of Fig. 3. The course of the blood among the cells is shown as be- 

 fore (B-B). A detail of the lymphatic system is added (Ly.). 

 The drawing is severely conventional. Two branches of the lym- 

 phatic are represented as beginning with open mouths so situated as 

 to receive the surplus fluid directly from the interstices of the tissue. 

 A third is connected with a blind sac. There is at present some dis- 

 agreement as to which is the more typical mode of origin. 



capable of transforming the soluble fibrinogen into the 

 insoluble fibrin. 



Lymph. This term is usually made to stand for the 

 fluid outside the blood-vessels. Used in this way, it 

 includes the liquid filling the microscopic intervals between 

 neighboring cells, the larger spaces which often occur in 

 the loosely woven connective tissues, and also the contents 

 of an inconspicuous system of tubular channels known as 

 lymphatics. A recent writer, Starling, has suggested 



