250 THE BLOOD. [CH. X. 



distributed between the plasma and the corpuscles. The 

 concentration in the blood increases after the ingestion of 

 considerable amounts of glucose or cane sugar, but only 

 increases after a meal of starch if the subject is abnormal. 

 The extent to which the blood sugar rises after taking 

 sugars depends on the rate at which the tissues, especially 

 the liver, can assimilate the carbohydrate. If the blood 

 sugar rises beyond 0-12 per cent, the condition is known as 

 hyperglycaemia. This is generally followed by the excre- 

 tion of easily detectable amounts of glucose in the urine, or 

 glycosuria, the severity of which varies with the degree of 

 hyperglycaemia, and also on the permeability of the 

 kidney to glucose. It must be noted that in certain 

 individuals the kidney is abnormally permeable to sugar, 

 so that marked glycosuria may exist without hyper- 

 glycaemia. This condition is known as "renal diabetes," 

 or "diabetes innocens," this latter term being applied 

 because it is not associated with the evil effects of the other 

 types of diabetes. The rate at which the liver can assimi- 

 late sugar, or the "tolerance for sugar/' is partially depend- 

 ent on the activities of various organs, such as the pituitary, 

 suprarenal and thyroid glands. Tolerance is best deter- 

 mined by blood analyses at appropriate intervals after 

 administration of glucose : the amount in the urine being 

 dependent on the renal permeability. 



310. Detection of glucose in blood. Into a small flask 

 measure 15 cc. of distilled water. Add 3 cc. of fresh defibrinated 

 blood obtained from a slaughter house. Mix to lake the corpuscles. 

 Heat to boiling, and keep the fluid boiling for a few seconds. Add 

 4 cc. of 1-25 per cent. " colloidal " (" dialysed ") iron, adding it drop 

 by drop and constantly agitating the flask. The proteins are 

 completely precipitated. Add a " knife point " of solid potassium 

 sulphate (to precipitate any excess of iron), and shake till it has 

 dissolved. Filter through a small paper. To 5 cc. of the clear filtrate 

 apply Cole's test for glucose (Ex. 104). A distinct positive test is 

 obtained. To another portion of the filtrate apply the picric acid 

 test (Ex. 108), controlling the latter by doing a blank test with an 

 equal volume of water. 



