340 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
the tenth day of pregnancy, since from the tenth to the thirteenth day 
seems to be a particularly important period in the development of the 
lens. It is then growing rapidly and becomes surrounded by a rich 
vascular network that later disappears. From four to seven cubic 
centimeters of the sensitized fowl-serum were injected intravenously 
into the pregnant rabbits at intervals of two or three days for from 
ten days to two weeks. Several rabbits died from the treatment and 
many young were killed in utero Of sixty-one surviving young from 
mothers thus treated, four had one or both eyes conspicuously defect- 
ive and five others had eyes which were clearly abnormal. It is 
possible that still others were more or less affected, since we judged 
only by obvious, visible effects. We found later in some of the 
descendants of these individuals that rabbits which passed for normal 
during their earlier months subsequently manifested traces of defects 
in their lenses or in other parts of the eye. 
The commonest abnormality seen in both the original subjects 
and in their descendants was partial or complete opacity of the lens, 
usually accompanied by reduction in size. Other defects were cleft 
iris, persistent hyaloid artery, bluish or silvery color instead of the 
characteristic red of the albino eye, microphthalmia and even almost 
complete disappearance of the eyeball. Taking into account the 
, method of enbryological development, however—the relation of lens, 
optic cup, and choroid fissure—the defects are probably all attributable 
to the early injury of the lens. In some cases, both among originals 
and descendants, an eye microphthalmic at birth may undergo fur- 
ther degeneration such as collapse of the ball and what appears to bea 
resorption as if some solvent were operating upon it. The eyes of the 
mothers apparently remained unaffected. This is probably due to 
the fact that the lens tissue of the adult rabbit is largely avascular 
and therefore did not come into contact with the injected anti- 
bodies. 
That the changes in the eyes of the fetuses resulted from the action 
of lens antibodies is indicated by the fact that in not one of the forty- 
eight controls obtained from mothers which had been treated with 
_ unsensitized fowl-serum or with fowl-serum sensitized to rabbit tissue 
other than lens, was there evidence of eye-defects, and I may add, 
that among the hundred or more young obtained later from mothers 
which were being experimented upon with various types of sera or 
protein extracts, for other purposes, not a single case of eye-defect 
has appeared. 
