I02 wherry: reply to dr. tutton's discussion 



posed of two interpenetrating simple ones. The disagreement 

 over this point, therefore, is merely a matter of definition of terms, 

 Dr. Tutton preferring to use "interpenetrating point-system" 

 for what the writer would call a "compound space-lattice." 

 Substitution of the one term for the other would not alter the 

 conclusions reached in the original paper to the slightest degree. 

 It should be noted, further, that the view that molecules rather 

 than atoms occupy the points or nodes of space-lattices has been 

 rather definitely disproved by the very X-ray study of crystals 

 which started the present discussion. 



To summarize: in the paper under discussion, the writer 

 assembled the data for a number of crystals, in the assignment 

 of which to symmetry classes one method of study gives results 

 which conflict with those of other methods of study. He presented 

 an interpretation of the relations which appeared to him capable 

 of reconciling these discordant results, involving the new con- 

 ception that crystals may belong to one symmetry class with 

 respect to some properties and to another class with respect 

 to other properties. Dr. Tutton apparently feels that the 

 present views of crystallography are adequate to explain all 

 past (and future) crystallographic observations. Rather than 

 recognize that diamond, pyrite, etc., belong simultaneously to 

 two different classes, depending on what property is considered, 

 he prefers to ignore observations which do not accord with the 

 one of these symmetry classes which for one reason or another 

 he wishes to accept for each substance. In diamond, he overlooks 

 the Class 31 habit and etch-figures, in pyrite the Class 28 habit 

 and electrical phenomena, and so on. The writer does not 

 believe that ignoring results which do not suit a preconceived 

 theory is the proper scientific spirit, and prefers to modify or 

 revise current ideas when necessary to explain undeniable ob- 

 servational facts, even though this may lead to his being accused 

 of putting forward "speculations built on incorrect crystal- 

 lography." 



