170 SPECIAL PHYSIOLOGY 



From a standard gastric juice prepare the following dilutions, 

 using 0.1 per cent. HC1 as a diluent. It is scarcely necessary to saj 

 that the greatest care should be taken (1) to make all measurements 

 with precision, and (2) to thoroughly shake each dilution before 

 drawing off material for the next lower dilution. 



(a) Standard artificial gastric juice 10 c.c. + l c.c. moist fibrin. 



(6) 1 :10 standard artificial gastric juice 10 c.c. + l c.c. moist fibrin, 



(c) 1:100 standard artificial gastric juice 10 c.c. + l c.c. moisl 

 fibrin. 



(d) 1:1000 standard artificial gastric juice 10 c.c. + l c.c. moisl 

 fibrin. 



(e) 1:10,000 standard artificial gastric juice 10 c.c. + l c.c. moisl 

 fibrin. 



(/) 1:100,000 standard artificial gastric juice 10 c.c. + l c.c. moist 

 fibrin. 



(g) 1:1,000,000 standard artificial gastric juice 10 c.c. + l c.c. 

 moist fibrin. 



Keep tubes in incubator or water-bath at 38 to 40 C. Note 

 (1) time required to dissolve fibrin completely; (2) time required to 

 change all acid albumin to proteose or peptone. Will one-millionth 

 standard gastric juice digest fibrin at all? Will a lower dilution 

 (one-ten-millionth) digest it? If so, how dilute, and how long a 

 time required? 



VI. GASTRIC DIGESTION (Continued). 



Experiments and Observations (Continued). (9) To Determine 

 the Influence of the Hydrochloric Acid of the Gastric Juice upon 

 Putrefaction in the Stomach. It has been determined that the hydro- 

 chloric acid in the stomach destroys, under favorable conditions, at 

 least the non-pathogenic forms of bacteria. Let us determine the 

 strength of acid necessary to destroy the common bacteria of putre- 

 faction. To each tube used in experiment (7) add a minute drop 

 of any putrefying fluid. If the contents of a tube serve as a good 

 culture field, any drop of the fluid may be found to be swarming 

 with bacteria within a few hours. Within a few hours after infecting 

 the tubes examine under high power 700 to 1000 diameters a drop 

 of the contents of each tube. While making the observations take 

 care not to contaminate one tube with the contents of another. That 

 the tubes containing 5 per cent, or 2 per cent, or 1 per cent, hydro- 

 chloric acid will be found to be free from bacteria goes without 

 saying. Just how weak may the acid be and destroy the bacteria ? 

 How weak may the acid be and retard their development? Could 

 one readily drink enough liquid at a meal to change the stomach 

 from a sterilizing field to a culture field for the bacteria of putre- 

 faction ? 



