Influence of Environment 219 



births, and weak and sickly offspring (Fig. 74). He and Papani- 

 colaou have studied the offspring of alcoholized parents to the 

 fourth filial generation and while the deleterious effects ultimately 

 disappear they attribute this to the elimination of those germ 

 cells, embryos and developed individuals that were most injured 

 and to the introduction of normal germplasm by crossing with un- 

 treated animals ; consequently the final survivors may be stronger 

 and more vigorous than the controls in which the weak are pre- 

 served along with the strong. 



Pearl found that the offspring of alcoholized chickens were on 

 the whole stronger than those from normal animals and he 

 attributes this to the elimination of weaker germ cells and em- 

 bryos, so that only the most sturdy survive. The work of both 

 Stockard and Pearl leaves no grounds for doubting that alcohol 

 kills or injures many germ cells and Stockard has demonstrated 

 that such injured cells may give rise to defective individuals and 

 that this injury may persist through two or three generations. 

 The facts that spermatozoa are affected even more than ova and 

 that the injury persists to the third filial generation show that the 

 chromatin of these cells is injured. Undoubtedly chromatin as 

 well as cytoplasm may be injured by various unfavorable condi- 

 tions, and if the injury is not too great it may persist through 

 several generations and may cause defective development ; but this 

 is probably a different thing from the "inheritance of an acquired 

 character" ; its effects are seen not in particular characters but in 

 a general weakening of development; not in imitative changes in 

 genes, but in their temporary injury. 



In venturing to apply Stockard's discoveries to human beings 

 it should not be forgotten that his guinea pigs were alcoholized 

 to a degree far greater than ever occurs in man. Some of them 

 that were five years old had been kept intoxicated for more than 

 four years. It is probable that the use of alcoholic beverages never 

 produces such serious effects on germ cells as in the case of these 

 guinea pigs which were compelled to inhale the fumes of strong 



