REPRODUCTION 83 



weighed on the same notch until they were 

 seven years old, then one gained half a pound 

 more than the others." When they were little 

 girls, one of them confided one day to a friend 

 that she had been bathed three times that 

 morning, while the others confessed that they 

 had not been bathed at all, an accident that 

 emphasized their complete bodily identity at 

 that period. Their lives must have been, in- 

 deed, a modern " Comedy of Errors." But for 

 us they are significant in that they show how 

 enormously powerful in determining traits was 

 that infinitesimally small amount of chromatic 

 material contained in the one microscopic egg 

 from which they all came, a power which when 

 spread through three persons instead of one 

 seems still to be undiminished. But we must 

 remember that the human body, like that of 

 many other animals, is often very sensitive to 

 minute amounts of material. Cats are known 

 to be affected by 0.0001 of a milligram of ad- 

 renalin, and our olfactory organs are stimu- 

 lated by 0.000,000,002 of a milligram of mer- 

 captan. Is it, therefore, after all, so surprising 

 that 0.000,004 of a milligram of chromatic 

 material should have so profound an influence 

 on our development ? Small as these amounts 



