THE ART OF SCIENTIFIC INVESTIGATION 



diseases. When an investigation on influenza was planned, 

 ferrets were included among a long list of animals it was 

 intended to try and infect sooner or later. However, some time 

 before it was planned to try them, it was reported that a colony 

 of ferrets was suffering from an illness which seemed to be 

 the same as the influenza then aflfecting the people caring for 

 them. Owing to this circumstantial evidence, ferrets were 

 immediately tried and found susceptible to influenza. Afterwards 

 it was found that the idea which prompted the tests in ferrets 

 was quite mistaken for the disease occurring in the colony of 

 ferrets was not influenza but distemper ! ^ 



( 1 2) A group of English bacteriologists developed an effective 

 method of sterilising air by means of a mist made from a 

 solution of hexyl-resorcinol in propylene-glycol. They conducted 

 a very extensive investigation trying out many mixtures. This 

 one proved the best; the glycol was chosen merely as a suitable 

 vehicle for the disinfectant, hexyl-resorcinol. Considerable 

 interest was aroused by the work because of the possibility of 

 preventing the spread of air-borne diseases by these means. 

 When other investigators took up the work they found that the 

 effectiveness of the mixture was due not to the hexyl-resorcinol 

 but to the glycol. Subsequently, glycols proved to be some of 

 the best substances for air disinfection. They were only intro- 

 duced into this work as solvents for other supposedly more active 

 disinfectants and were not at first suspected as having any 

 appreciable disinfective action themselves." 



(13) Experiments were being conducted at Rothamsted 

 Experimental Station on protecting plants from insects with 

 various compounds, when it was noticed that those plants treated 

 with boric acid were strikingly superior to the rest. Investigation 

 by Davidson and Warington showed that the better growth had 

 resulted because the plants required boron. Previously it had 

 not been known that boron was of any importance in plant 

 nutrition and even after this discovery, boron deficiency was for 

 a time thought of as only of academic interest. Later, however, 

 some diseases of considerable economic importance — " heart- 

 rot " of sugar beet for example — were found to be manifesta- 

 tion of boron deficiency. ^"^ 



(14) The discovery of selective weed-killers arose unexpectedly 



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