128 CHARLES R. STOCKARD AND GEORGE N. PAPANICOLAOU 



each individual receives per day, per month, or per year, but, 

 as we have pointed out before, such knowledge would be of no 

 advantage either to us or to others in estimating the results of 

 these experiments. No two individuals would be affected to 

 exactly the same degree by the same dose, and as is the case 

 with man the later influences of the treatment no doubt differ 

 in different individuals. There is also no particular interest 

 here in the amount of alcohol used, since our primary problem is 

 whether or not an active chemical substance may be given in 

 sufficient amounts to the parent mammal to produce effects upon 

 its offspring or descendants by modifying its germ-cells, or in 

 the case of the pregnant female by acting through the mother on 

 the developing embryo. 



We have thus employed, as stated in our previous reports, a 

 simple physiological index of the amount of treatment, giving 

 enough each day to perceptibly influence or intoxicate the ani- 

 mals, but not enough to produce a complete drunken stupor. 



Animals may remain for very long times in these treatment 

 tanks w^hen alcohol fumes are not present without in any way 

 suffering for want of breathing space. This method has many 

 advantages so far as the general health of the individual animal 

 is concerned over drinking alcohol into the stomach, as will be 

 discussed in the following section. 



The only object in choosing alcohol as the treating agent is on 

 account of the fact that considerable knowledge exists as to its 

 physiological actions on certain animal tissues and it is knoAvn to 

 be an active organic substance that might produce effects. It 

 had further been used by one of us (Stockard, '10) in producing 

 various developmental abnormalities in fish embryos which could 

 be treated directly with diluted alcohol, and the general nature 

 of the effects on these embryos had been studied. A final advan- 

 tage in using alcohol in such experiments is the ease with which 

 it may be administered to the animals by the inhalation method 

 which we have described. 



Caging and care of ayiimals. All of the guinea-pigs, both the 

 experimental and the control animals, are kept in the same type 

 wooden cages. These are group cages, each containing twenty 



