ON THE DOMESTIC FOWL. 245 



11. Material and Methods. 



General Plan. 



The general plan of this investigation involves some features 

 which have not been incorporated in earlier researches in this general 

 field. In the first place, it was thought desirable to use tzvo pure 

 breeds of poultry for the foundation stock in the experiments rather 

 than one, and in consequence of this make the offspring of the 

 treated animals F^ crossbreds rather than pure-bred birds. The 

 primary consideration in favor of this plan was that, by its adoption, 

 a much more manifold opportunity seemed likely to be given to test 

 any putative influence of the poisons on the germ plasm. It should 

 be possible in an experiment of this sort to see whether in F^ the 

 usual conditions as to Mendelian dominance are in any manner or 

 degree disturbed by the administration of the poisons to the parents. 

 Further, when the F^ individuals from treated parents are them- 

 selves bred there will be an opportunity to apply the most delicate 

 of all genetic tests for the composition of the germ plasm, namely 

 the test of segregation in F, and succeeding generations. 



In the investigation here reported the foundation stock used came 

 from pedigreed strains of two breeds, Black Hamburgs and Barred 

 Plymouth Rocks. Both of the strains used have been so long pedi- 

 gree bred by the writer, and used in such a variety of Mendelian 

 experiments, that they may be regarded as " reagent strains," whose 

 genetic behavior under ordinary circumstances may be predicted 

 with a degree of probability amounting practically to complete cer- 

 tainty. Furthermore the results of crossing these two breeds recip- 

 rocally have been thoroughly studied by the writer. 



Substances Used and Mode of Administration. 



In the present investigation three different series of birds were 

 started. To the birds in one series was administered 95 per cent, 

 ethyl alcohol. To those in the second series was administered 

 methyl alcohol, and to those in the third series, ether. 



The method followed in these experiments for the administration 

 of the poisons was essentially that which has been used by Stockard, 

 namely the method of inhalation. 



