CONCLUSIONS 285 



number of animals may fail to obtain results com- 

 parable with those which we have described. How- 

 ever, if a sufficiently large number of animals is sub- 

 jected to a given experimental procedure, it will be 

 found that results similar to ours will be obtained in 

 a sufficient majority of instances to warrant the con- 

 clusions which we have stated. This of course is a 

 common experience in biological investigations of 

 all kinds. 



As an aid to any investigator who wishes to repeat 

 or extend such experiments, we have appended a short 

 selected list of procedures taken from our protocol 

 books in the hope that these may prove of service to 

 anyone who wishes to venture into this interesting field 

 of investigation. These experiments have not been 

 chosen because of the particular value of the results 

 obtained, but rather as an illustration of the technique 

 developed in our laboratory. 



The writer fully appreciates that many of his de- 

 ductions and concepts will meet the opposition usu- 

 ally accorded new theories. This is desirable, since 

 such opposition frequently constitutes the impetus 

 necessary to provoke experimental researches which 

 will finally prove or disprove the validity of the con- 

 cept. 



