392 V. BLOOD LIPIDS 



uniformity of technic is obtained in a single laboratory than is possible 

 when several laboratories are involved, and this may, in part, explain the 

 greater constancy in these figures. The average phospholipid content in 

 whole blood expressed in milligram per cent was as follows: five dogs, Av. 

 339 (310-370) 223 ; and seven dogs, Av. 350 (320-400). 224 When blood 

 plasma was used, the phospholipid content was reported as 350 (280-500) 

 for seven dogs, 224 and 400 (250-610) for six dogs. 7 - 225 



c. Cholesterol. The variations in averages reported for blood chole- 

 sterol in dogs are as great as those for total blood lipids. While Terroine, 208 

 using the Windaus digitonin method, cited an average blood cholesterol 

 value in blood plasma of 122 milligram per cent (90-152) for seven dogs, 

 Bloor and associates, employing a colorimetric procedure, reported mean 

 values of 174 (130-240, five dogs), 223 and 230 (180-300, seven dogs) 7 - 224 

 for whole blood, and 220 (150-370, seven dogs) 224 and 100 (80-120, six 

 dogs, modified procedure) for blood plasma. The cholesterol values ob- 

 tained in the serum of four normal dogs were reported by Mayer and Schaef- 

 fer 206 as ranging between 89 and 116 mg. 100 g. moist weight. It is evident 

 that one cannot state a precise value for the level of cholesterol in normal 

 dogs. 



(2) Normal Variations in the Blood Lipids 

 of the Same Individual 



Although one accepts the fact that considerable variations may obtain 

 in the level of a blood constituent in different individuals of a group of 

 normal animals of the same species and of a similar dietary background, it 

 is of considerable interest to inquire as to what degree of constancy in the 

 level of the lipid components may be noted in a single animal over a period 

 of time. It is difficult to establish the experimental conditions in such a 

 manner that changes in diet, environmental conditions, as for instance the 

 season of the year, age, etc. , do not play a role. 



Terroine 207 - 226 reported results on the blood lipids in dogs for periods as 

 long as eleven months which show a good degree of uniformity. In experi- 

 ments on six dogs over periods as long as six months, 208 the maximum varia- 

 tion in total lipids from the mean was 169 mg. per 100 g. In studies on 

 nine dogs over a week, Bloor 222 found that the average variation of each 

 dog from his average was only 6.0%, while the greatest variation noted was 

 12.0%. The mean value for total lipids in all tests was 590 milligram per 

 cent. 



226 E. F. Terroine, J. physiol. path, gen., 16, 386-397 (1914). 



