PREOXAXry. 127 



8 inches. The othei* measurements of Maros and Foals yielded similar 

 results, and give an idea of the expulsive ellbrts the uterus must make 

 to expel the fcetus. In the case tirst cited, it may be admitted that 

 the pelvis of the Mare had, approximately, the following dimensions : 

 inlet of the pelvis — sacro-pubic diameter, inches ; inlet of the pelvis 

 — bi-iliac diameter, 8^ inches. In comparing these dimensions with 

 those of the Foal to which it gave birth, it is obvious that the biscapulo- 

 humeral and bicoxo-femoral diameters of the latter could be easily 

 accommodated by the bi-iliac diameter of the mother, as they are less 

 by 1^ and ^ inch ; but it is not the same with regard to the sacro-pubic 

 diameter, which is less by nearly three inches than the sterno-dorsal 

 line of the fcietus. It is therefore evident that, in order to pass through 

 the pelvis, this line must be diminished at least by three inches. In 

 the second edition of his work, he gives the measurements of other 

 parts of the body of the fcttus, but their consideration leads to com- 

 plexity. In studying the table he has drawn up of these various 

 measurements in the Foal, he thinks an idea may be formed of the force 

 of the uterine contractions necessary to expel the foetus; and again 

 remarks that, even when the largest circumference of Foals only slightly 

 exceeds that of the pelvic inlet of the Mare, or is equal to it, a great 

 amount of accommodation must nevertheless take place in the thorax 

 of the young creature, as the sterno dorsal diameter is greater than the 

 sacro-pubic diameter of the mother. When gestation is prolonged the 

 fa'tus is still larger, and the difliculty in its expulsion is increased. 



With regard to the Bovine species, nine Cows were tabulated. The 

 first, the smallest, was 11| hands high, and the width of the croup 18J 

 inches ; the weight of the fcetus was about sixty-two pounds, the 

 sterno-dorsal diameter 10.\ inches, the biscapulo-humeral G,',-, inches, 

 and the bicoxo-femoral 7i\ inches. Another Cow was l-2\ hands higli, 

 the width of croup IS^^ inches; the weight of the fa-tus was about 

 seventy-three pounds, the sterno-dorsal diameter 10^ inches, the 

 biscapulo-humeral G inches, and the bicoxo-femoral 8^'^ inches. With 

 a Cow 12? hands high, and croup 18 inches in width, which had 

 experienced a protracted accouchement in consequence of the size of 

 the calf, and which had aborted the previous year, the weight of 

 the fa-tus was sixty-six pounds, the sterno-dorsal diameter 15 inches, 

 the biscapulo-humeral 7^ inches, and the bicoxo-femoral 8^ inches. 

 The circumference of the chest of the Calf being so much greater than 

 the inlet of the Cow's pelvis, explains why it is tliat parturition in 

 this animal, even when normal, is longer than in the Mare. 



With regard to the Ovine and Caprine species, the fa-tus is rela- 

 tively smaller in dimensions than the Calf ; while in animals which are 

 usually multiparous, the young are always less in circumference than 

 the pelvic inlet, though when it happens that they have only one foetus 

 this is often so increased in size that birth becomes very protracted, 

 and may even be impossible. 



CHAPTER V. 

 Pregnancy. 



Gkst.\tion, or i^rcgnancy, comprises the period during which the female 

 animal carries its young while this is undergoing development. Its 

 consideration is of much moment, and we will, with regard to it, study 



