62 BOVINE OBSTETRICS 



zontal line. Poullet called it the line of tonic uterine con- 

 traction. In the cow this line is 44 to 48 mm. above zero, and 

 shows no fluctuations (St. Cyr and Violet). In the woman, the 

 uterus during the periods of intermission is almost at rest, the 

 line being nearly horizontal ; the line of tonic uterine con- 

 traction in the woman is 15 to 20 mm. above zero. As soon 

 as contractions begin, the mercury column constantly rises 

 and falls until a period of rest occurs. 



A labor pain is made up of a series of momentary 

 contractions, followed by relaxation and diminution of uterine 

 tension. Each contraction produces a rise of mercury from 

 80 to 110 mm. (St. Cyr and Violet). By means of the toco- 

 graph, we may measuie the force exerted by the contracting 

 uterus and the movements of its auxiliary muscles, viz.: 

 abdominal compression. 



Each cubic centimeter of the foetus experiences during 

 a strong contraction a pressure of 200 to 300 gr. (St. Cyr and 

 Violet). When the surface of the calf, barring the extremities 

 — that is, up to the patellae and elbows — represents 32 dm.^, 

 the calf receives a pressure of 610 to 960 kg. During violent 

 throes — that is, a continuous tonic contraction, known as 

 tetanus uteri — the uterus becomes anaemic, resulting possibly 

 in asphyxia of the foetus. Should a torsion of the uterus or a 

 closed OS uteri be present, or the expulsion of the foetus 

 retarded ou account of its excessive size or abnormal position, 

 labor pains are unsuccessful, and in due time uterine fatigue 

 sets in. When the contractions after exhaustive labor are 

 weak and of short duration, one speaks of an atony of the 

 uterus ; while limited uterine contractions, with a long period 

 of rest, are termed an inert uterus. Total absence of contrac- 

 tions are the result of exhaustion or paralysis of the uterus. 



Labor pains, according to their effects, are divided into: 

 (1) Preparatory pains; (2) expulsive or labor pains; (8) post 

 partum pains. 



Preliminary stage. — Preparatory pains are such uterine 

 contractions where the abdominal pressure is limited. These 

 pains loosen a portion of the foetal placenta and open the 



