SECT. 6] OF THE EMBRYO 945 



drugs on birth weight, reference may be made to the papers of 

 Hanson & Heys. 



In this connection it is interesting to find general agreement 

 existing that the larger the litter in a mammal the smaller each 

 individual is. Thus Bluhm found the following figures in mice: 



No. of embryos Weight in gm. of 

 in litter each individual 



And the same holds true for the guinea-pig (Ibsen & Ibsen), the 

 rabbit (Kopec) and the pig (Hammond). 



