68 



G. MATTHEW FYFE. 



present in the specimen was estimated, 

 taken from some forty. 



Table I shows the results in six cases 



Table I. — The Effect of Incuhation on the Sugar in 0'2 ex. Blood. 



Control Percentage after 



percentage. 



Case. 



•081 



•097 



•102 



•13 



•097 



131 



incubation. 



•082 



•097 



•106 



•13 



•097 



•134 



No appreciable change in the sugar content occurs on incubation of 0'2 c.c. 

 blood in 2^8 c.c. saline solution at 37° C. for half an hour. It should be stated 

 here that throughout the experiment and also throughout the entire diastase 

 investigation, strict aseptic precautions were observed to exclude the possibility 

 of bacterial action during incubation. 



THE PROPOSED METHOD DESCRIBED. 



Into one of two 100 c.c. Erlenmeyer flasks 1'8 c.c. of 0^9 per cent, saline 

 solution and 1 c.c. of 0^1 per cent, starch solution {i. e., 1 mg. starch) is accu- 

 rately pipetted, while into the other (control flask) exactly 2'8 c.c. of 0*9 per cent, 

 sahne solution is introduced. 0"2 c.c. blood is withdrawn from the finger into 

 a special MacLean pipette* and carefully ejected into the fluid of the first 

 flask, the point of the pipette being held beneath the surface of the solution, 

 while the flask is held at an angle. The pipette is rendered free from blood 

 by repeated washing with the clear fluid into which the blood has just been 

 delivered. The flask is then gently shaken with a circular movement so as to 

 mix thoroughly the blood and the solution. A second sample of 0^2 c.c. blood 

 is similarly delivered and washed into the control flask. Both flasks, provided 

 with rubber stoppers, fitted with capillary points, are placed in a water-bath, 

 the temperature of which is accurately maintained at 37° C. Incubation is 

 allowed to proceed for exactly half an hour, at the end of which time the flasks 

 are removed and 21 c.c. of MacLean's acid sodium sulphate solution is added. 

 In the case of the first flask the addition should be made immediately on 

 removal from the water-bath so as to stop the action of the diastase. The 

 subsequent steps in the estimation are precisely as described by MacLean. 

 Briefly the treatment is as follows : The flasks are heated till the boiling- 

 point is just reached. 1 c.c. dialysed iron is added to each and after cooling 

 under the water tap the contents are filtered. To 20 c.c. of each filtrate is 

 added 2 c.c. alkaline copper solution. The resulting solutions are then boiled 

 for six minutes over a flame suitably adjusted to effect distinct boiling in one 

 minute forty seconds. At the end of that period the flasks are immediately 

 plunged into cold water and cooled thoroughly. 2 c.c. of 75 per cent. HCl 

 (or H2SO4) are added, and after effervescence has finished and after standing for 

 one minute with occasional agitation, the iodine content of the solutions is 

 found by titration with N/400 sodium thiosulphate. During titration, in the 

 case of the first flask, a variation of colour is seen ranging from dark amber to 

 * To be obtained from Hawksley & Son, Wigmore St., London. 



