MODIFICATION OF THE GERM-CELLS IN MAMMALS 127 



pigs and the normal control lines are due to the treatment ad- 

 ministered to the alcoholic lines. We further believe that if 

 the differences which do exist between the alcoholics and control 

 are so slight that the crudest mathematical calculations are in- 

 sufficient to indicate their presence, the experiment has then 

 produced no data of biological interest or importance since 

 conducted on animal material of such complexity as a group of 

 mammals. This statement is made with no intention or pre- 

 sumption to question the real importance and value of modern 

 biometrical methods, but is only what we believe should apply 

 to this particular experiment. 



3. EXPERIMENTAL METHOD AND THE CARE OF ANIMALS 



Throughout these experiments alcohol has been administered 

 to the guinea-pigs by a method of inhalation which was devised 

 in the beginning. The animals to be treated are placed in fume 

 tanks fully described and illustrated in an earlier comm^unica- 

 tion (Stockard, '12) and absorbent cotton soaked with com- 

 mercial 95 per cent ethyl alcohol is placed on the floor of the tank 

 beneath a wire screen on which the animals stand. The fumes 

 of evaporating alcohol very soon saturate the atmosphere of 

 the tanks and the guinea-pigs introduced into this saturated at- 

 mosphere are allowed to remain until they show distinct signs 

 . of intoxication. During the earlier years of the experiment they 

 remained for one hour each day in such tanks, but during the 

 past twelve months we have increased the treatment to two 

 hours per day for the males and three hours for the females. 



This longer treatment is much better in that the animal, of 

 course, gets a larger dose and its tissues may become more quickly 

 influenced by the treatment. The animals may remain until 

 they are completely intoxicated, in which case they are unable 

 to walk, and therefore lie in a typical drunken stupor, or they 

 may be affected to such an extent that they attempt to walk 

 and in so doing stagger and fall in a manner characteristic of 

 the drunken state. The amount of treatment here employed, 

 however, does not produce complete intoxication. 



It would be perfectly possible with an elaborate system of 

 measurements to determine exactly the quantity of alcohol lumes 



