CHAPTER XII 



EDEMA 1 



As the term edema indicates the excessive accumuhitioii of lymph 

 (which may be either normal or modified in composition ) in the cells, 

 intercellular spaces, or serous cavities of the body, the problems of 

 edema are inseparably connected Avith the consideration of the proc- 

 esses of physiological formation and removal of lymph. For many, 

 years the study of these processes has been a favorite field of investi- 

 gation by physiologists, and the great battle-place of the "vitalistic" 

 and "mechanistic" schools; and to this day the forces that determine 

 the formation of lymph and its subsequent absorption have not been 

 completely understood. By the application of the principles of phys- 

 ical chemistry to the problem, however, great advances have recently 

 ])een made, which seem to render our understanding of both lymph- 

 formation and its pathological accumulation in the tissues much 

 clearer and more nearly accurate than they were before. AVe shall 

 first consider, therefore, the physiological formation of lymph, before 

 taking up the subject of edema. 



Composition of Lymph. — Lymph consists of material derived from two chief 

 sources. The greater part consists of fluid passing out of tlie capiUaries into 

 the tissue spaces: here it is modified by the addition of products of metabolism 

 derived from the tissue-cells, and by the sul)traction of materials tliat the cells 

 utilize in their metabolism. It is, therefore, essentially a modified blood plasma, 

 and the modifications the plasma undergoes are so slight tliat. under ordinary 

 conditions, lymph shows on analysis no considerable differences from blood 

 plasma, except a relative poverty in proteins, due chiefly to the impermeability 

 of the capillary walls for colloids. Its quantitative composition varies greatly, 

 depending upon the conditions under which it is collected, whether during 

 activity or rest, etc. Tiie following tables of analyses have been collected by 

 Ilammarsten: 



1 2 .*? 4 



Water 0.30.0 0.34.S 057.6 0.55.4 



Solids 00.1 05.2 42.4 44.6 



0.4 2.2 



.34.7 



35.0 



1 and 2 are analyses of lymph from tlie tliigli of a woman. .'! is from tlic 

 contents of sac-like dilated vessels of the spermatic cord, 4 is lymph from the 

 neck of a colt. 



lA complete bibliograpliy is given by Afeltzer. .\merican l\redicine, 1004 (S), 

 10 et seq. ; also bv Klemeiisiewicz, in Krehl and Marchand's Ihuullmeli d. allg. 

 Path., 1012, II (1), 341: ]\Iagnus. TTandlmeh d. Hiochem.. 1!)(1S, 11 |2), 90; 

 Gorhartz, ihid., ]>. 11(5. 



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