ARE ACQUIRED CHARACTERS HEREDITARY? 339 



Just what is a spontaneous change? No one has ever succeeded in 

 telling us. And we may suspect, though perhaps it is heresy to do so, 

 that it is a well-sounding phrase that is the equivalent of the three 

 words, "I don't know." Unwilling to admit of the modifying influence 

 of external agencies on the germ, such theorists resort to the fiction 

 of a spontaneous change. Coleridge somewhere has said, "What's 

 gray with age becomes religion." We have toyed so long with this 

 idea of germinal continuity and the invulnerability of the germ, that it 

 has become for some of us wellnigh sacrosanct. Living matter is 

 living matter wherever it may be found, but when it happens to be in 

 the germ-cells, verily, " this corruptible has put on incorruption and 

 this mortal immortality"! 



Now, no one to-day, qualified by his knowledge of embryology 

 and genetics to the right of an opinion, would, I think, deny that the 

 new organism is in the main the expression of what was hi the germ- 

 line, rather than of what it got directly from the body of its parents, 

 but does this fact necessarily carry with it the implication that the 

 germ is insusceptible to modification from without ? Is not the serum 

 of organisms with blood or lymph an excellent medium through which 

 external influences may operate upon it ? Is it not more reasonable 

 to postulate the origination of germinal changes through some such 

 mechanism as this than to attribute it to mysterious "spontaneous 

 changes"? 



With such thoughts hi mind I and my research associate, Dr. 

 E. A. Smith, set about making various tests. Without attempting 

 to tell you of our as yet unsuccessful attempts to secure cytolysins 

 which will operate in the developmental stages of such periodically 

 renewed structures as feathers, or to weary you with the history of our 

 various other failures of which there are an abundance I wish to 

 speak briefly about certain antenatal effects we secured in rabbits by 

 means of fowl-serum sensitized against rabbit crystalline lens, and of 

 the fact that such induced defects may become heritable. 



The crystalline lens of the rabbit was selected as antigen, and fowls 

 as the source of the antibodies. The lenses of newly killed rabbits 

 were pulped thoroughly in a mortar and diluted with normal saline 

 solution. About four cubic centimeters of this emulsion was then 

 injected intraperitoneally or intravenously into each of several fowls. 

 Four or five weekly treatments with such lens-emulsions were given. 

 Then a week or ten days after the last injection the blood-serum of 

 one or more of the fowls was used for injection into pregnant rabbits. 

 The rabbits had been so bred as to have the young advanced to about 



