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 in 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 in 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 fowlc 
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 
