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 afifected 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 



