THE FRACTIONAL METHOD OF GASTRIC ANALYSIS 221 



juice would be 2.2 = 4.84, and for the pure undiluted juice, 4.84X 

 16 = 77.44. 



Preparation of Mett Tubes (Christiansen's Method). The 

 liquid portions of the. whites of several eggs are mixed and strained 

 through cheesecloth. The mixture should be homogeneous and 

 free from air bubbles. It is best to allow the egg-white to stand 

 for two or three hours in a vacuum desiccator more completely to 

 remove air. A number of thin-walled glass tubes of 1 to 2 mm. 

 internal diameter are thoroughly cleaned and dried and cut into 

 lengths of about 10 inches. These are sucked full of the egg-white 

 and kept in a horizontal position. Into a large evaporating dish 

 or basin 5 to 10 liters of water are introduced and heated to boiling. 

 The vessel is then removed from the fire and stirred with a ther- 

 mometer until the temperature sinks to exactly 85 C. The tubes 

 filled with egg-white are immediately introduced and left in the 

 water until it has cooled. The tubes thus prepared are soft boiled, 

 more easily digested than hard boiled tubes, and free from air 

 bubbles. The ends are sealed by dipping in melted paraffin or 

 sealing wax (preferably the latter), and the tubes can be kept thus 

 for a long time. When ready for use mark with a file and break 

 into pieces about three-quarter inch long. After cutting, the 

 tubes should be immediately introduced into the digestion mixture 

 or may be kept a short time under water. Tubes whose ends are 

 not squarely broken off must be rejected. 



The digestibility of different egg-whites varies widely. Hence 

 in making up a new set of tubes if we wish our results to be com- 

 parable these tubes must be standardized against those first pre- 

 pared. This may be done by running simultaneous tests with 

 tubes from the two series, using the same gastric juice and com- 

 paring the lengths of the columns digested in each case. Christian- 

 sen's method of preparing tubes of the same digestibility is to be 

 preferred. He proceeds as in the original preparation of the tubes 

 except that as the water cools from 90 to 80 C. a single tube con- 

 taining the new egg-white is dropped in at each degree change of 

 temperature, that is at 90, 89, etc. Pieces of each of these tubes 

 as well as of the original standard tubes are then allowed to digest 

 simultaneously in portions of the same gastric juice. One of these 

 tubes should show a digestibility equal to that of the standard 

 tubes. For example the tube coagulated at 88 C. may show 

 the proper digestibility. Then the new series of tubes should be 



