778 
E. S. FRY. 
of the foetal membranes to the walls of the uterus, or that it is 
especially frequent in animals in a state of debility. Prof. Mc¬ 
Intosh claims that the immediate cause of inversion is relaxation 
of the ligaments of that organ, whose duty it is to retain it in its 
position. Fleming says a flaccid, iron-contracted uterus after 
birth, with a weak cervix and dilated os, and relaxed broad liga¬ 
ments, we should certainly look upon as a predisposing con¬ 
dition ; and this is most likely to be present in lymphatic ani¬ 
mals, or those suffering from atony, brought about by debility 
through disease, or bad or insufficient food, or exposure to 
weather. Others claim that the accident occurs only in animals 
of a plethoric or lymphatic temperament and their consequent 
laxity of tissue ; and it is often the case that cows which are 
soft, and kept on food that is better suited for the production of 
milk than flesh, are most frequent subjects of inversion. In my 
own experience I have noticed that when these spasmodic con¬ 
tractions of the uterus (called labor pains) take place, there is 
some cause of irritation in the operation, and while the sympa¬ 
thetic nerves are in all probability those which are most con¬ 
cerned in the uterine contractions, as they are the motor nerves 
of the organ, their influence is called forth by this irrita¬ 
tion. The physiology of parturition teaches us that the expul¬ 
sive force by which parturition is effected resides in the un¬ 
striped muscular fibres of the uterus, which cause the organ to 
contract in a rhythmical and somewhat peristaltic manner, the 
contractions of the abdominal muscles and diaphragm being 
merely auxiliary, and as parturition progresses, and the separa¬ 
tion between the uterus and foetus increases during each regular 
pain, the whole of the uterus contracts, though the fundus does 
so most energetically, the longitudinal muscular fibres of the or¬ 
gan being more particularly brought into play. The cornua 
likewise contract, and are shortened through the action of the 
longitudinal fibres, and are brought nearer the body of the 
uterus, which is also shortened ; and as this shortening is always 
taking place in the direction of the cervix, it is here that the 
sum total of the expelling force is centred. It is this force,. 
