THE EXPERIMENTAL MODIFICATION OF GERM 



CELLS 



I. GENERAL PLAN OF EXPERIMENTS WITH ETHYL ALCOHOL AND 

 CERTAIN RELATED SUBSTANCES^ 



RAYMOND PEARL 



Maine Agricultural Experiment Station 



THREE FIGURES 



CONTENTS 



I. The problem .' 125 



II. Material and methods 128 



A. General plan 128 



B. Substances used and mode of a/dministration 132 



C. Foundation stock used in the experiments 138 



D. Time of beginning treatment 156 



E. Plan of matings in 1915 156 



F. Germinal dosage index 158 



G. Scope of present report 161 



III. Summary 161 



IV. Literature cited 162 



Although every variation is either directly or indirectly caused by some change in the surround- 

 ing conditions, we must never forget that the nature of the organization which is acted on essentially 

 governs the result. — Charles Darwin. 



I. THE PROBLEM 



One of the outstanding problems of genetics is that of the 

 origin of new heritable variations. With the passage of time 

 and the .accumulation of exact experimental data it becomes in- 

 creasingly clear that this factor is the basic one in all evolu- 

 tionary change, whether progressive or retrogressive. Just 

 now it is the fashion to speak of new heritable variations as 

 mutations, but such designation does not appear either to make 

 the facts concerned any different from what they were under 



' Papers from the Biological Laboratory of the Maine Agricultural Experi- 

 ment Station, No. 100. 



125 



