THE ART OF SCIENTIFIC INVESTIGATION 



probably all great investigators to follow up their discoveries and 

 not leave the trail till they had exhausted it. The story of 

 Bernard's experiments with digestion in rabbits recounted earlier 

 provides a good illustration of this poHcy. When Gowland 

 Hopkins found that a certain test for proteins was due to the 

 presence of glyoxylic acid as an impurity in one of the reagents, 

 he followed this up to find what group in the protein it reacted 

 with and this led to his famous isolation of tryptophane. Any 

 new fact is potentially an important new tool to be used for 

 uncovering further knowledge and a small discovery may lead 

 to something much greater. As Tyndall said : 



" Knowledge once gained casts a faint light beyond its own 

 immediate boundaries. There is no discovery so limited as not 

 to illuminate something beyond itself." 



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As soon as anything new is discovered the successful scientist 

 immediately looks at it from all possible points of view and by 

 connecting it with other knowledge seeks new avenues for investi- 

 gation. The real and lasting pleasure in a discovery comes not so 

 much from the accomplishment itself as from the possibility of 

 using it as a stepping stone for fresh advances. 



Anyone with a spark of the research spirit does not need to be 

 exhorted to chase for all he is worth a really promising clue when 

 one is found, dropping for the time being other activities and 

 interests as far as practicable. But in research most of the time 

 progress is difficult and often one is up against what appears to 

 be a " brick wall ". It is here that all resources of ingenuity and 

 method are required. Perhaps the first thing to try is to abandon 

 the subject for a few days and then reconsider the whole problem 

 with a fresh mind. There are three ways in which benefit may 

 be derived from temporary abandonment of a difficulty. It allows 

 time for "incubation ", that is for the subconscious to digest the 

 data, it allows time for the mind to forget conditioned thinking, 

 and lastly, by not doggedly persisting, one avoids fixing too 

 strongly the unprofitable lines of thought. The principle of 

 temporary abandonment is, of course, widely practised in every- 

 day life, as for example, in postponing the making of a difficult 

 decision until one has " slept on it ". Elsewhere the usefulness 

 of discussion has been stressed, not so much for seeking technical 



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