202 M. J. Karvonen 



the first values for the sodium and potassium concentration 

 of adult sheep erythrocytes, and found that they belong to the 

 "low potassium — high sodium" type. In 1937 Kerr observed 

 higher potassium concentrations, with a large variation 

 between individual sheep. In the determinations of Hallman 

 and Karvonen, the erythrocytes of the Finnish sheep turned 

 out to be — contrary to those of Abderhalden — of the "high 

 potassium — low sodium" type, containing still more potas- 

 sium than the red cells of Kerr's sheep. Sheep erythrocytes 

 thus show a large range of individual variations in the 

 electrolyte composition. 



The electrolytes are not the only constituents of the red 

 cells in which individual sheep differ. The solubility character- 

 istics of sheep haemoglobin obtained from different countries, 

 from different breeds, or from different sheep may also differ 

 (Karvonen, 1949; Karvonen and Leppanen, 1952). It was 

 natural, as a working hypothesis, to connect with each other 

 these differences in the red cell electrolytes and in the type 

 of haemoglobin. In the first five samples representing dif- 

 ferent breeds of sheep, haemoglobin prepared from the low 

 potassium erythrocytes actually showed a crystal habit 

 different from that of the high potassium cells (Karvonen 

 and Leppanen, 1952). 



Since these early attempts the red cell electrolytes of sheep 

 have become the subject of intense study. The individual 

 differences in the electrolyte composition have been shown to 

 be permanent characteristics (Evans, 1957). The occurrence 

 of different types of red cells in a number of breeds has been 

 studied, and the genetics of the inheritance have been worked 

 out (Evans, 1954, 1957; Evans and King, 1955; Evans et al., 

 1956; Evans and Mounib, 1957). 



The application of paper electrophoresis to sheep haemo- 

 globins has shown that though there is a definite association 

 between the electrolytes in the red cells and the haemoglobin, 

 this association is not absolute (Harris and Warren, 1955; 

 Evans et al., 1956; Evans, Harris and Warren). On the other 

 hand, the haemoglobin present in the red blood cells has an 



