THE SOURCE OF THE AMNIOTIC AND ALLANTOIC FLUIDS IN MAMMALS. 



87 



Our own few observations on the cow support Doderlein's results, as is shown in the 

 appended table (C) : — 



TABLE C. 



Weight of Foetus, 

 grms. 



No. 



Allantoic. 



Amniotic. 



Present Obser- 

 vations. 



D6DERLEIN. 



Present Obser- 

 vations. 



DdDERLBIN. 



About 100 

 600 to 700 . 

 3000 to 4000 . 

 About 9000 . 



2 

 3 

 3 

 1 



332 



700 

 1800 

 3900 



90 



850 

 2000 

 6500 



247 

 2730 

 2500 



460 



160 



2000 

 3200 

 1200 



In the pig we have made seven observations, which give the following average 

 amounts of fluid in each gestation sac with different lengths of embryo : — 



Length of Embryo 



Amniotic Fluid 



Allantoic Fluid 



in cms. 



m c.cms. 



in c.cms. 



2-5 



11 



135 



30 



14 



130 



3-0 



1-5 



144 



80 



170 



135 



10-0 



41-0 



170 



17-0 



75-0 



155 



24-0 



70-0 



180 



This shows the same increase in the amniotic fluids as occurs in the sheep, with the 

 same comparatively small increase in the amount of allantoic fluid. 



Amount. — In the animals examined, the amniotic fluid is at first small in amount, 

 but rapidly increases, and in the sheep and cow reaches its maximum about the middle 

 of pregnancy, after which it undergoes no very marked change in the sheep, but very 

 markedly decreases in the cow. The allantoic fluid in the earlier part of pregnancy is 

 larger in amount than the amniotic, but in the later stages it may show hardly any 

 increase, as in the sheep, or it may increase enormously, as in the cow. 



Possibly these different relations depend upon the extent to which the amniotic 

 fluid is swallowed by the foetus and re-excreted through the patent urachus into the 

 allantoic vesicle. It is further possible that, in the middle period of pregnancy, before 

 the muscular structures round the urethra are formed, the urine secreted passes equally 

 into both sacs, but that in the later months in some animals, e.g. the cow, it may gener- 

 ally pass into the allantoic sac, and only occasionally by micturition into the amniotic. 



Specific Gravity. — The allantoic fluid shows a marked increase in specific gravity. 

 The amniotic fluid shows hardly any increase in its specific gravity. 



TRANS. ROY. SOC. EDIN. VOL. XLVI. PART I. (NO. 3). 



13 



