EFFECTS OF PLACENTAL EXTRACTS 103 



reproduction. Their function is co-ordinative and con- The placenta 

 tinuous, not intermittent ; and such organs are part of secretion™ 

 the soma of the individual. 



This digression is in part repetition, but I have given 

 my own views prominence in this place because the 

 placenta of all structures in the animal economy should 

 never have been chosen for a seat among the elect. 



In the first place, the placenta has a very short 

 phylogenetic history : it is a structure of late mammalian 

 origin. In the second, the placenta is a foetal structure 

 and is not maternal, excepting in so far as the ovum is 

 maternal and in conjunction with the male contribution 

 forms the foetus. Third, the placenta is merely a 

 temporary occupant of the uterus. 



Let us now shortly consider the evidence that has 

 been adduced to prove that the placenta gives rise to an 

 internal secretion of value to the maternal economy. 

 This evidence is chiefly related to investigations con- 

 cerning the effects of extracts of the placenta. 



THE PHYSIOLOGICAL EFFECTS OF PLACENTAL EXTRACTS 



In 1907 Dixon and Taylor 1 announced that placental Effects of 

 extracts have a powerful pressor effect, especially in extracts 1 . 

 regard to the involuting uterus. This, indeed, it was 

 said, is t^ie reason why animals devour their placentae 

 after parturition ! Rosenheim 2 , however, shortly after- 

 wards showed very definitely that the pressor effect 

 which had been obtained was due to the pressor sub- 

 stances derived from the amino-bodies found in putre- 

 fying meat 3 - 4 , which are formed in the placenta when 

 it is not properly preserved. 



1 Dixon, W. E., and F. E. Taylor, Brit. Med. Journ., 1907, vol. ii, 

 p. 1156. 



2 Rosenheim, 0., Journ. Physiol., 1909, vol. xxxviii, p. 337. 



3 Abelous, J. E., H. Ribaut, A. Soulie, and G. S. P. Toujan, Compt. 

 Rend. Soc. Biol, 1906, vol. lx, pp. 463 and 530; J. E. Abelous and 

 H. Ribaut, Compt. Rend. Soc. Biol, 1908, vol. lxiv, p. 907. 



4 Barger, G.,and G. S. Walpole, Journ. Physiol, 1909, vol. xxxviii, 

 p. 343. 



