GESTATION 



1031 



Zakroav, M. X., AND Zarrow, I. G. 1953. Anemia 

 in the rabbit dvu'ing pregnancy and following 

 treatment with water soluble o\arian extracts. 

 Endocrinology, 52, 424. 



Zeiner, r. N. 1943. .Studies on the maintenance 

 of pregnancy in the white rat. Endocrinology, 

 33, 239. 



Zondek, B., and Sulmax, F. 1945. The mecha- 

 nism of action and metabolism of gonadotro- 

 phic hormones in the organism. Vitamins & 



• Hormones, 3, 297. 



ZrcKERMAN, S. 1935. The Aschheim-Zondek di- 

 agnosis of pregnancy in the chimpanzee. Am. 

 J.Phvsiol., 110, 597. 



Aclcleiitluin 



Several reports on an exteroceptive block 

 to pregnancy in mice appeared since this 

 manuscript was completed. In a series of 

 three articles, Bruce (Nature, London, 184, 

 105, 1959; Science, 131, 1526, 1960; and J. 

 Reprod. Fertil, 1, 96, 1960) has shown that 

 exposure of newly mated, female mice to 

 strange males caused an inhibition of preg- 

 nancy that ran as high as 80 per cent. Prior 

 removal of the olfactory bulbs abolished the 

 reaction. The pregnancy block in tliis in- 

 stance consisted in a failure of the blasto- 

 cysts to implant. 



