186 



PHYSIOLOGY OF FARM ANIMALS 



[CH. 



in many other mammals. In the horse and other Ungulata, how- 

 ever, this does not happen. In the Carnivora the vilH are confined 

 to a zone or belt, in ruminants they occur in ckimps or cotyledons 

 corresponding to the cotyledonary papillae Avhich in these animals 

 protrude from the uterine mucous membrane, while in the horse 

 and pig the villi are scattered. 



The highly develoj)ed uterine glands supply a secretion (called 



Fig. 96. Foetal circulation, advanced period (after Colin, from Fleming, 

 Messrs Bailliere, Tindall and Cox). A cotyledons, B umbilical vein which 

 communicates with C and D, venae portae (in liver) and with ductus 

 venosus (opening into F, posterior vena cava, G right venticle, H pulmonary 

 artery, I ductus anteriosus (uniting H and J), J aorta, L umbilical arteries. 



in ruminants the uterine milk) which helps to nourish the develop- 

 ing foetus. 



The beginning of gestation is marked by a change in the 

 character of the mother. The pregnant cow and sheep ' settle ' or 

 tend to fatten in the early months, and graziers take advantage 

 of this fact to get the animals into good condition for market. 

 Mares which were previously troublesome and difficult to work 



