374 THE PHYSIOLOGY OF REPRODUCTION 



i-o\\s u-strus is said to take place in spite of there being a corpus 

 luttMim present, but when this is so the periods are shortened to 

 twelve or fifteen hours instead of the normal duration which is 

 said to be double that time, and the cows if served in this condition 

 fail to conceive. It is probable that in spite of oestrus taking place 

 >\ ulation fails to occur. The continuance of the corpus luteum 

 as an apparent result of vaginitis or venereal disease may be due to 

 the irritation of the generative organs, and is perhaps comparable 

 to the normal stimulus set up by pregnancy, which results in the 

 persistence of the corpus luteum in polyoastrous as in moncestrous 

 animals, or to the mechanical and artificial stimuli induced by Leo 

 Loeb in the uterus of the guinea-pig, which is followed not only by 

 the formation of decidual cells at the place where irritation is 

 experienced, but by the persistence of the luteal bodies in the ovary. 



Williams states that sterility as a result of the persistent corpus 

 luteum can be remedied by squeezing out this organ from the ovary, 

 the operation being performed through the rectum or vagina, and 

 that oestrus recurs within a short time of the corpus luteum being 

 eliminated. According to the clinical records of the New York- 

 State Veterinary College, at Cornell University ninety-five per cent. 

 of the cattle so treated conceived at the first subsequent service. 

 Albrechtsen, 1 however, throws some doubt on the practical value 

 of this method of treatment. Hess, 2 on the other hand, records a 

 number of observations and experiments which are confirmatory of 

 those of Williams. 



According to Loeb, 3 deciduomata (i.e. nodules having the structure 

 of decidua) can be produced experimentally in the uterine mucosa 

 of the guinea-pig by making a number of transverse and longitudinal 

 cuts so as to break the continuity of the tissue. The nodules 

 originate through a proliferation of the interglandular connective 

 tissue. Loeb states further that this can only happen during a 

 certain definite period after the occurrence of copulation or heat. 

 The changes cannot be induced on the first day after heat, nor after 

 the tenth day, but deciduomata are readily formed between the third 

 or fourth and eighth or ninth days. The uterus is therefore most 

 responsive when freshly formed corpora lutea are present in the 

 ovaries and therefore at a different time from that at which the 

 proliferating effect on the mammary gland is produced (see pp. 619 



1 Alliirrhtsen, Th<> Steriliti/ of Cows, English Translation, Chicago, 1917. 



- Hess, J)i<; Sti-rilitnt (/,-.< IHinli'K, iln-i' I'lrk-i'innnnj it ml /}'/, ///u)tg, Hannover, 

 1921. <'/. also Opperniann, St'-rilitnt //<T Hamtierc, Hannover, 1922. 



3 Loeb (L ), "The Production of Deciduomata, and the Relation between 

 the Ovaries and the Formation of the Decidua," Jour. Amer. Med. Amoc., vol. 1., 

 (6th .Inn.-) l!)os : M,.,i;,;,l /.Vro/v/, vol. Ixxvii., (25th June) 1910; Arch, fur 

 Kiitiri.-lc.-.M*,-!.., vol. xxxii., 1911 ; forgery. Obstetrics, and Gynecologtj, vol. xxv., 

 1917 ; and .lour. K.r/>. .)/></.. vol. xxv., 1917. 



