€0 BOVINE OBSTETRICS 



Many observations corroborate these theories ; for in- 

 stance, the occurrence of an abortion just at a time when 

 in the unimpregnated state oestrum woald set in ; the expul- 

 sion of a so-called calf mummy during the period of oestrum. 



Franck found, on conducting a post mortem of cows which 

 died during or after parturition, one or more matured Giaaffian 

 vesicles almost ready to rupture in the ovary devoid of the 

 corpus luteum. This led him to the deduction that the ovary 

 which did not furnish the impregnated ovum might create 

 reflectorily a genital hypersemia by the pressure of the swollen 

 vesicles upon the sensory nerves, same as during oestrum. 

 According to EUenberger, the act of birth, the changes which 

 the gravid uterus undergoes, as well as the periodical expul- 

 sive contractions following fecundation, are simply hereditary. 



1. — Labor Pains — Dolores. 



Generally speaking, the words "labor pains" represent 

 the expulsive forces ; in a more concrete sense, the uterine 

 contractions. The contractions begiu in the muscles of the 

 broad ligaments, next contracts the uterus, and in the further 

 course of parturition the muscular elements of the vagina and 

 vestibule participate. These contractions are periodical ; they 

 occur now and then, with definite intermissions. 



Various causes induce uterine contractions. The uterus 

 may contract as the result of irritations originating in the 

 cerebellum, medulla oblongata and spinal cord (Spiegelberg, 

 Frankenhauser, Korner, Obernier); but the uterus itself 

 harbors nerve centres, stimulation of which, produces con- 

 tractions. Sensibility is conducted via the spinal nerves. 

 We already stated that advanced pregnancy means a hyper- 

 sesthetic state of the uterus. Excitability uf the uterus also 

 increases with rise of temperature and hypersemia of this 

 organ. We further know that dyspnoic blood — that is, blood 

 laden with carbon dioxide and wanting in oxygen — is exciting 

 to the uterus. In all probability the stimulus leading to 

 ■contraction arises in the uterine nerve centres. Mechanical 



