The Amnion 351 



An increase of this fluid constitutes what is known as dropsy of 

 the amnion, which accumulation, in the cow, may sometimes reach 

 the enormous amount of 20 or more gallons and prove so burden- 

 some as to prevent the patient from arising when down, because 

 of the great weight of the accumulated fluid. (See Dropsy of 

 the Amnion.) 



In some cases, especially in the embryo of the cow, the 

 amnion apparently becomes contracted during the early stages of 

 its formation and causes an eversion of the somatopleuric portion 

 of the embryo, resulting in the condition which we know as 

 fissura ventralis or schistosontus reflexiis. In this deviation, no 

 body cavity is formed and the internal viscera, derived from 

 the splanchnopleure, lie free within the chorion. In other words, 

 the constriction and infolding of the splanchnopleure to constitute 

 the intestine proceeds. The constriction which should ex- 

 ternally mark the division between the fetal and vitelline por- 

 tions of the somatopleure, to constitute the umbilicus, fails to 

 develop; the amnion contracts; the spinal axis of the embryo 

 bends ventralwards, in a way pas.ses out through the non-con- 

 stricted umbilic area and the embryo, so to speak, turns inside- 

 out. The spinal axis of the fetus becomes sharply doubled 

 dorsally and the somatopleuric portions lie as a partially everted 

 sac with its peritoneal surface presenting externally. This ab- 

 normality constantly causes serious difficulties at the time of 

 parturition and frequently taxes the resources of the obstetrist 

 to overcome them. This will be more fully considered when 

 dealing with dystocia. vSee Figs. 71 and 72. 



Other interesting defects in the development of the amnion 

 occur, one of the most frequent being adhesion of this membrane 

 to the epiblast of the fetus, largely upon the head, by which, 

 at the time of birth, the fusion between the skin of the fetus and 

 its membranes offers an important or serious obstacle to its ex- 

 pulsion. 



The liquor amnii contains albumin, sugar, urea and other ele- 

 ments of urine and, in many cases, especially in the foal, also 

 some masses of meconium. The avenue by which each of the fluid 

 substances reaches the amniotic cavity has not been fully shown. 

 Some hold that the fluid transudes into the cavity from the 

 amnion itself, coming indirecth' of course from the blood of 



