SYNOVIAL FLUID. 45 



freely the articulating surfaces. In a horse of medium size 

 and in good condition, examined immediately after death, 

 Colin found 1*6 fluidrachms in the shoulder-joint; 1*9 

 drachms in the elbow-joint ; 1'6 drachms in the coxo-fernoral 

 articulation ; 2*2 in the femoro-tibial ; and 1*9 in the tibio- 

 tarsal. 1 



When perfectly normal, the synovial fluid is either color- 

 less or of a pale yellowish tinge. It is so viscid that it is 

 with difficulty poured from one vessel to another. This 

 peculiar character is due to the presence of an organic sub- 

 stance called synovine. When this organic matter has been 

 extracted and mixed with water, it gives to the fluid the 

 peculiar viscidity of the synovial secretion. The reaction 

 of the fluid is faintly alkaline, on account of the presence of 

 a small proportion of carbonate of soda. The fluid, espe- 

 cially when the joints have been much used, usually con- 

 tains in suspension pale epithelial cells and a few leucocytes. 

 The following is the composition of the synovial fluid of the 

 human subject : a 



Composition of the Synovial Fluid. 



Water 928'00 



Synovine (called albumen) 64'00 



Principles of organic origin (belonging to the second class of 



Robin) not estimated. 



Fatty matter 0'60 



Chloride of sodium 



\ 



6'00 

 Carbonate of soda 



Phosphate of lime 1'50 



Ammonio-magnesian phosphate traces. 



The observations of Frerichs indicate considerable vari- 

 ations in the composition and general characters of the 

 synovial fluid, dependent upon use of the joints. In a stall- 

 fed ox the proportion of water to solid matter was 969*90 

 to 30'10; and in animals that took considerable exercise, 



1 COLIN, op. cit. t tome ii., p. 440. 



2 ROBIN, JLefons sur les humeurs, Paris, 1867, p. 276. 



