TRANSMISSION OF INDUCED EYE-DEFECTS Bid 
which survived the injections of the lens-sensitized serum was 
bred again, usually of the same male, and several of them were 
bred repeatedly, yet not a trace of eye defect was observable in 
their progeny. 
It is a noteworthy fact that once the defects were established, 
without any subsequent treatments they became more and more 
pronounced in successive generations. In some of the fifth- and 
sixth-generation forms, for example, there was more of a tendency 
for both eyes to be affected than in earlier generations, and also 
an increased tendency for the eyeballs of the imperfect eyes to be 
very small—almost to the vanishing point. It would seem, 
therefore, that some cumulative influence was at work. As 
already pointed out, this might be due, in some measure at 
least, to the fact—if it is a fact—that a number of constitutional 
factors or modifying factors are concerned in the inheritance of 
the defects and that these have been accumulated by the inten- 
sive breeding practiced. However, there would seem to be a 
limit to this considerably short of complete disappearance of the 
eye. 
The other alternative is, possibly, that the degenerating eyes 
are themselves directly or indirectly originating antibodies or 
other chemical substances in the blood-serum of their bearers 
which in turn affect the germ-cells. From the fact that such 
antibodies as isolysins can be established, it does not seem im- 
‘probable that changed conditions in tissues would induce the 
formation of antibodies in an animal’s own body. These once 
established, should be as effective in modifying germinal factors 
as corresponding antibodies introduced into the fetus through 
the placenta of the mother. 
If this second alternative is true, then there opens up a wide field 
of possibilities as to the influence of the various parts of a body 
on the antecedents of such parts in the germ cells borne by that 
body. For such a condition would afford a ready means of modi- 
fying germinal factors by changes in the correlative organs of the 
parent, the blood serum of any organism with blood being the 
medium through which the influence is conveyed from the pa- 
rental organ to the germ. As long as there is little change in the 
