SCIENTIFIC METHOD 73 



a gap in the vascular series, but his demonstra- 

 tion made it a logical certainty that a bridge 

 across this gap was in existence" (Gotch, 1906, 

 p. 47). Although it was not till 1661 that Mal- 

 pighi saw the blood flowing through transparent 

 capillaries from the smallest arteries to the 

 smallest veins, Harvey's demonstration might 

 have passed at once into physiological science 

 (which was far from being its reception) for the 

 simple reason that it was an observed fact that 

 the blood goes on ceaselessly flowing throughout 

 life. The system works, therefore the unseen 

 bridge across the gap must be there. 



FORMULATION. The final step in scientific 

 method is to sum up what has been proved in 

 terms as clear and terse as possible. A theory is 

 stated, a formula is invented, or, more frequently 

 a new set of facts is brought into subjection to 

 an old law. The theory must fit the facts; it 

 must be a complete and consistent description; 

 its terms must be either directly experimental, 

 or accessible to experimental tests; and it must 

 be impersonal to this extent, that it will appear 

 valid to all who can appreciate the evidence. 



"The final touchstone," Prof. Karl Pearson 

 says, "is equal validity for all normally consti- 

 tuted minds." Moreover, the theory must be 

 compared with already established conclusions. 

 If there is any discrepancy between the new and 



