450 A MANUAL OF PHYSIOLOGY 



important abnormal substances iound in solution in the urine. 

 Normal urine, as has been stated, contains a trace of dextrose, 

 but so little that it cannot be detected by ordinary tests, and 

 for practical purposes it may be considered absent. Dextrose is 

 the sugar found in the urine in diabetes. In the urine of nursing 

 mothers lactose may be present. Pentoses, sugars with five 

 carbon atoms in the molecule (instead of six, as in the hexoses, of 

 which group dextrose is a member), may also occasionally occur 

 in urine. Pentoses give the ordinary reduction tests for sugar, 

 and yield osazones, but do not ferment with yeast. Various plants 

 contain pentoses, and when these are eaten the pentoses are ex- 

 creted in the urine, but in cases of true pentosuria they originate 

 in the body, possibly from nucleo-proteins. The condition has 

 not the same sinister significance as diabetes. Specific toxic 

 substances produced by bacterial action have been demonstrated 

 in the urine in certain diseases. Red blood-corpuscles and 

 leucocytes (pus corpuscles, white blood-corpuscles, mucus cor- 

 puscles) are the chief organized deposits ; but spermatozoa may 

 occasionally be found, as well as pathogenic bacteria e.g., the 

 typhoid bacillus ; and in disease of the kidney casts of the renal 

 tubules are not uncommon. These tube-casts may be composed 

 chiefly of red blood-corpuscles, or of leucocytes, or of the epithe- 

 lium of the tubules, sometimes fattily degenerated, or of struc- 

 tureless protein, or of amyloid substance. Abnormal crystalline 

 substances, such as the amino-acids, leucin (Fig. 169), and tyrosin 

 (Fig. 170), and cystin (Fig. 163) may be on rare occasions 

 found in urinary sediments ; but generally the unorganized 

 deposits of pathological urine consist of bodies actually contained 

 in, or obtainable from, the normal secretion, but present in 

 excess, either absolutely, or relatively to the solvent power of the 

 urine. Cystin is of interest because of its relations to the 

 sulphur of the protein molecule (p. 332). It is not found in the 

 normal organism. It very occasionally forms calculi in the 

 bladder. There are individuals who constantly pass as much as 

 one-fourth of all the sulphur in the form of cystin, without any 

 other symptoms. 



Various amino-acids are present in solution in the urine in 

 many pathological conditions. Of these the least soluble are 

 leucin and tyrosin, and this is the reason why they are most easily 

 detected. A general reaction for amino-acids is their precipita- 

 tion as sparingly soluble compounds (/^-naphthalinsulphones) 

 by ^-naphthalinsulphochloride in the presence of an alkali 

 (sodium hydroxide). In acute yellow atrophy of the liver 

 leucin and tyrosin have been found in large amounts in the 

 liver itself, as well as in the urine. In phosphorus poisoning 

 these amino-acids, as well as glycocoll, have been detected in 



