252 



PHYSIOLOGY 



CHAP. 



and the expulsion of the placenta, by the contractions of the 

 uterine muscles, which continue to occur at intervals during the 

 first three days of the puerperium, and are accompanied by painful 



FIG. 100. Genital canal of a woman recently delivered. (Bumm.) 1, internal orifice (ring of 

 contraction) of uterus ; 2, external orifice; 3, internal orifice (ring of contraction); 4, 

 external orilice. 



sensations, the after-pains, which are of special intensity in the 

 pluripara. During these contractions the muscular fibres are 

 forced together and compress the vessels passing between them. 

 Owing to the diminished supply of blood, the protoplasm of the 

 muscular fibres becomes turbid, little drops of fat are formed 



