OBSERVATION 



ance. This he confirmed by ahemately feeding and starving 

 them, a process which he found altered the reaction of their 

 urine as he had anticipated. This was a nice observation and 

 would have satisfied most investigators, but not Bernard. He 

 required a " counterproof ", and so fed rabbits on meat. This 

 resulted in an acid urine as expected, and to complete the experi- 

 ment he carried out an autopsy on the rabbits. To use his words : 



" I happened to notice that the white and milky lymphatics 

 were first visible in the small intestine at the lower part of the 

 duodenum, about 30 cm. below the pylorus. The fact caught 

 my attention because in dogs they are first visible much higher 

 in the duodenum just below the pylorus." 



On observing more closely, he saw that the opening of the 

 pancreatic duct coincided with the position where the lymphatics 

 began to contain chyle made white by emulsion of the fatty 

 materials. This led to the discovery of the part played by pan- 

 creatic juice in the digestion of fats.^^ 



Darwin relates an incident illustrating how he and a colleague 

 failed to observe certain unexpected phenomena when they were 

 exploring a valley : 



" Neither of us saw a trace of the wonderful glacial phenomena 

 all around us; we did not notice plainly scored rocks, the 

 perched boulders, the lateral and terminal moraines."' 



28 



These things were not observed because they were not expected 

 or specifically looked for. 



While watching the movements of the bacteria which cause 

 butyric acid fermentation, Louis Pasteur noticed that when the 

 organisms came near the edge of the drop they stopped moving. 

 He guessed this was due to the presence of oxygen in the fluid 

 near the air. Puzzling over the significance of this observation he 

 concluded that there was no free oxygen where the bacteria were 

 actively moving. From this he made the far reaching deduction 

 that Ufe can exist without oxygen, which at that time was thought 

 not possible. Further he postulated that fermentation is a meta- 

 bolic process by which microbes obtain oxygen from organic sub- 

 stances. These important i^leas which Pasteur later substantiated 

 had their origin in the observation of a detail that many would 

 not have noticed. 



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