128 OBSTETRICAL PHYSIOLOGY. 



it in this chapter from a normal or physiological point of view — noticing 

 the anatomical and functional alterations attending it, the mode of 

 recognising it, its duration in various species of animals, and the excep- 

 tional departures from the usual law with respect to the number of 

 young produced. 



It has already been remarked that soon after fecundation the 

 female becomes generally more tranquil, and indifferent to the male, 

 who also does not seek her company so ardently as before ; while a cer- 

 tain amount of sluggishness may be observed in her movements. These 

 changes in habit become more marked as time advances, and along 

 with them the other alterations referred to, and now to be described. 



SECTION I.— MODIFICATIONS IX THE UTERUS DURING PREGNANCY. 



With the development of the foetus, the uterus undergoes important 

 anatomical and physiological modifications ; while the system of the 

 mother also, as stated, participates more or less generally in the 

 phenomena which mark the period of gestation. The modifications 

 and phenomena are worthy of attentive notice, not only from the 

 importance they hold with regard to the reproduction of animals, but 

 also from the practical issues involved in the study. 



The anatomical changes in the uterus are those relating to its volume, 

 structure, form, situation, and direction. 



Voluvie. 



With regard to volume, we have seen that during and after copulation 

 the uterus is congested, and that, when conception has taken place, the 

 thin pulpy secretion corresponding to the decidua of the human female 

 covers its internal surface. The vessels, distended with blood, gradu-. 

 ally enlarge to a great size — from the smallest to the largest forming 

 most intricate and beautiful plexuses on and in the texture of the organ. 

 The coats of the arteries are thickened to compensate for their disten- 

 sion, and the additional labour they have to perform ; while the veins 

 are still more enlarged in calibre. The lymphatics are likewise aug- 

 mented in number and dimensions ; and the nerves, w^hich were com- 

 paratively small in the unimpregnated state, enlarge and anastomose 

 so freely as to compose a network similar to that of the vessels — the 

 increase taking place in the nerve terminations, not in the nerve sub- 

 stance. 



In uniparous animals in which the foetus is developed in one of the 

 cornua, this becomes greatly increased, and appears to be continuous 

 with the body of the uterus, the other horn looking like a mere appen- 

 dage projecting from its side ; but with multiparous females the'cornua 

 increase nearly alike in size, owing to their being each occupied by the 

 foetuses (Fig. 65). 



Structure. 



These changes add to the thickness and density of the uterus ; but 

 there are others still more remarkable. While the organ is increasing 

 in volume, becoming rounder, acquiring a greater capacity, and its 

 cervix widening, its proper structure is exaggerated to an extraordinary 

 degree. This exaggeration, however, does not occur equally through- 

 out ; it is most marked in the cornua of multiparous creatures at the 

 points where the young are fixed — in Euminant animals at the situa- 

 tion of the cotyledons, and in Solipeds at the part of the body of the 



