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THE AMEBIC AN NATURALIST [Vol. XL VII 



required to suppose that the wild form contains a num- 

 ber of factors which by mutation have been lost. We may 

 still do so, but we are not forced to do so. We are free 

 to suppose with Morgan that merely a "readjustment" 

 has taken place, and to make no assumption as to its 

 nature, unless we choose to do so. This course does not 

 prejudice the investigator of the physiology of color pro- 

 duction but leaves him free to frame such hypotheses as 

 will from his point of view best meet the situation. He is 

 not bound down, for example, to a hypothesis of chromo- 

 gen and ferments and so tempted with Eiddle to throw 

 over all Mendelism simply because Mendelians have in 

 his opinion misinterpreted chemical facts. 



That terminology evidently is most desirable which 

 states demonstrated facts most clearly and simply, and 

 makes fewest assumptions as to their explanation. Other- 

 wise the investigator may be led to conclusions based on 

 his terminology rather than his facts, and this can lead 

 only to disaster. 



