466 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 

 mto 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 earher 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 embryological 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 be a 

 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. 



