ii8 OBSTETRICAL PHYSIOLOGY. 



birth, and the register for 1868 gave the following results. The weight 

 varied from 31 to 35 kilogrammes — the average being 32^ kilogrammes. 

 The males were a little heavier than the females. In twenty-eight 

 instances, the average weight of the calf compared with that of the cow 

 was as 2 to 31. 



The average weight of one hundred lambs weighed at the Alfort pens, 

 is given by Magne as about 4 kilogrammes for both sexes. The males 

 were heaviest. 



With regard to dimensio7is^ Saint-Cyr justly regrets the paucity of obser- 

 vations which have been made on this important point. It is of course 

 well known that, in a general wa}^, the foetus is larger than the pelvic 

 opening through which it has to pass at birth, but we have to ascertain 

 how much larger it is than that canal, and what is the amount of reduc- 

 tion in volume to which it has to submit in passing the outlet of the 

 pelvis. Rainard merely states that some measurements he had made, 

 gave the diameter of the thorax of calves, from withers to sternum (verti- 

 cal) as from 1034^ to 11 inches; and the diameter from side to side 

 (transversal) as 63^ to 7 inches. Saint-Cyr, anxious to arrive at some 

 definite conclusion in the matter, in order the better to understand the 

 mechanism of natural parturition, as well as to gain a knowledge of 

 how to surmount the difficulties of protracted labor, undertook some 

 researches in this direction. His object was to ascertain the depth and 

 width of the chest, and width of croup of the foetus', these being the 

 dimensions which it is most important to compare with the different 

 diameters of the pelvis of the mother, so as to understand how the 

 former may accommodate themselves to the latter. He gives the 

 name of sierno-dorsal line to the verticle measurement taken from 

 the summit of the highest dorsal spines to the sternum, and biscapulo- 

 humeral line to the distance measured from one scapulo-humeral artic- 

 ulation to the other ; while the bicoxo-femoral line is the measure- 

 ment of the croup from one coxo-femoral articulation to the other. 

 From the measurements in the Horse species, we find that a Mare 

 measuring a trifle over fifteen hands in height, and whose pelvis 

 was nearly nineteen inches in width, brought forth a foal weighing 

 slightly less than thirty pounds, and whose sterno-dorsal measurement 

 was nearly twelve inches, biscapulo-humeral line 7^ inches, and bicoxo- 

 femoral line nearly 8 inches. The other measurements of Mares and 

 foals yielded similar results, and give an idea of the expulsive efforts the 

 uterus must make to expel the foetus. In the case first cited, it may be 

 admitted that the pelvis of the Mare had, approximately, the following 

 dimensions : inlet of the pelvis — sacro-pubic diameter, 9 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 bi- 

 scapulo-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 34^ 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 foetus. It is therefore evident that in order to pass through 

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



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

 first, the smallest, was 11 3^ hands high, and the width of the croup 18^ 

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

 dorsal diameter 10^ inches, the biscapulo-humeral 6iV inches, and 



