92 THE AMERICAN NATURALIST [Vol.LVI 



tissue-elements and their germinal correlatives ever occur 

 in animals without being introduced by man ? Do animals 

 ever form such antibodies or other equally active sub- 

 stances against their own tissues! It is obvious, since 

 tissues persist intact under conditions of normal physio- 

 logical equilibrium, that they are not being subjected to 

 such influences, or if they are, that they resist them. As 

 a matter of fact, Romer,^ using the complement-fixation 

 technique, found that the serum of adult human beings 

 may possess antibodies for their own lens proteins. It 

 seems reasonable to suppose that if the tissues of an 

 animal became injured or displaced in some way, or met- 

 abolically unbalanced, immunity reactions might be es- 

 tablished against them. We have some evidence that 

 such is the case. During the late war, for example, it 

 was found that toxic reactions resembling anaphylactic 

 shock often followed extensive injuries of the soft tissues. 

 The matter can be tested experimentally. Because of 

 their distinctive nature and the ease with which they may 

 be isolated, I chose spermatozoa for such an experiment.'' 

 I found that a rabbit will build antibodies against its own 

 spermatozoa when these are injected into its blood- 

 stream; also, that rabbits injected with rabbit sperma- 

 tozoa not only develop antibodies in their blood, but also 

 have their own spermatozoa greatly weakened, a condi- 

 tion shown in vitro by their lessened resistance to anti- 

 sera. This clearly shows that an animal can on occasion 

 build antibodies against its own tissues; and since anti- 

 bodies can apparently directly or indirectly affect germ- 

 cells, it seems reasonable to suppose that such influences, 

 especially if continued over a long period of time, might 

 be one source of germinal variations. 



It is known from the experiments of Kuntz^ and others 

 that the blocking off of the ductus deferens of on.e testis 

 may indnoe dogciieration of the germinal epithelium, not 

 only of tliat testis, but of the other as well. Inasmuch 

 as tile -iM iiimtozoa in the testis on the operated side 

 must <lic and lie icsorbed, is it not probable that in this 

 process spermatotoxins have been formed which have 

 then attacked the living germ-cells of the other testis'? 

 Again, we are familiar with the fact that oculists fre- 



" Paper in press, Jour, Exp. ZooJ. 



