THE ART OF SCIENTIFIC INVESTIGATION 



explanation of the usual. When an irregularity is noticed, look 

 for something with which it might be associated. In order to 

 make original observations the best attitude is not to concentrate 

 exclusively on the main point but to try and keep a look-out 

 for the unexpected, remembering that observation is not passively 

 watching but is an active mental process. 



Scientific observation of objects calls for the closest possible 

 scrutiny, if necessary with the aid of a lens. The making of 

 detailed notes and drawings is a valuable means of prompting 

 one to observe accurately. This is the main reason for 

 making students do drawings in practical classes. Sir MacFarlane 

 Burnet has autopsied tens of thousands of mice in the course 

 of his researches on influenza, but he examines the lungs of 

 every mouse with a lens and makes a careful drawing of the 

 lesions. In recording scientific observations one should always 

 be as precise as possible. 



Powers of observation can be developed by cultivating the 

 habit of watching things with an active, enquiring mind. It is 

 no exaggeration to say that well developed habits of observation 

 are more important in research than large accumulations of 

 academic learning. The faculty of observation soon atrophies 

 in modem civilisation, whereas with the savage hunter it may 

 be strongly developed. The scientist needs consciously to develop 

 it, and practical work in the laboratory and the clinic should assist 

 in this direction. For example, when observing an animal, one 

 should look over it systematically and consciously note, for in- 

 stance, breed, age, sex, colour markings, points of conformation, 

 eyes, natural orifices, whether the abdomen is full or empty, the 

 mammary glands, condition of the coat, its demeanour and 

 movements, any peculiarities and note its surroundings including 

 any faeces or traces of food. This is, of course, apart from, or 

 preliminary to, a clinical examination if the animal is ill. 



In carrying out any observation you look deliberately for 

 each characteristic you know may be there, for any unusual 

 feature, and especially for any suggestive associations or relation- 

 ships among the things you see, or between them and what 

 you know. By this last point I mean such things as noticing 

 that on a plate culture some bacterial colonies inhibit or favour 

 others in their vicinity, or in field observations any association 



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