342 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
substance of the mature organ in question and the material ante- 
cedents of such an organ as it exists in the germ. 
Biologically considered, the most significant fact is that specific 
antibodies can induce specific modifications in the germ-cell. Whether 
these antibodies are transmitted from the mother’s blood or engen- 
dered in that of the young would seem to be of secondary importance. 
It stands to reason that antibodies originated in an animal’s own blood 
will modify germinal factors if corresponding antibodies introduced 
from without can accomplish this. 
The whole question as to how important such a fact may be in 
contributing to an understanding of the causes of the germinal changes 
in organisms in general, which lead to variation and evolution, hinges 
on the question of whether changes in an animal’s tissue will induce 
the formation of antibodies or kindred active substances in its own 
body. We have steadily accumulating evidence that such reactions 
do occur. 
In our own laboratory, for example, after many attempts we have 
succeeded in securing a defective-eyed young rabbit from a mother 
of normal stock by injecting her repeatedly with pulped rabbit lens 
before and during pregnancy. Since the young rabbit in question has 
both eyes badly affected there can be no question that a rabbit can 
build antibodies against rabbit-tissue which are as effective as those 
engendered in a foreign species such as the fowl. We have likewise 
found it relatively easy to secure spermatoxins by directly injecting 
rabbits, both male and female, with rabbit spermatozoa. Moreover, 
a given male will develop antibodies against his own spermatozoa if he 
is injected intravenously with the latter. 
We are also securing evidence that serologic reactions induced in 
the fetus through operations on the mother are not mere passive trans- 
missions, but may become actively participated in by the tissues of the 
fetus. For example, female rabbits sensitized with typhoid vaccine 
followed by living typhoid germs may transmit to their young and 
even to their grand descendants the ability to agglutinate typhoid 
bacilli in serum diluted from 60 to 160 times. From the standpoint 
of heredity we have no reason so far for maintaining that this is 
anything but placental transmission, though we are going to practice 
immunization generation after generation for a number of generations 
to determine if a truly hereditary immunity will be established. How- 
ever, facts have come to light which show that there is more concerned 
in the operation than a mere transfer of antibodies from mother to 
