378 



ON INCREASE IN SIZE 



[PT. Ill 



amount after the middle of pregnancy, but this was not found to 

 be the case by Ibsen for the guinea-pig. Ibsen constructed from his 

 experimental data the interesting diagram shown in Fig. 28, which 

 shows the percentage of the whole system occupied by embryo, 

 placenta, decidua basalis, and amniotic fluid from the 20th day 

 onwards. The embryo does not rise in per cent, after the 55th day, 

 the placenta remains very much the same all through, the decidua 

 basalis is much smaller relatively at the end than at the beginning 



and so is the amniotic fluid. Up to the 50th day Ibsen found no 

 correlation between foetus-weight and placenta-weight, but after- 

 wards there is undoubtedly such a correlation, evidently due to 

 crowding. 



[d) Rabbit. Much less work has been done on this form than might 

 have been expected from its easy availability, but the figures of 

 Chaine (the standard ones) are given in Table 8 of Appendix i, 

 together with some early fragmentary ones of Fehling. Friedenthal 

 also gives a few data which are shown in Table 9. 



{e) Dog. Liesenfeld, Dahmen & Junkersdorf made a thorough 

 study of (unfortunately only 5!) dog foetuses. 



