ANIMAL MECHANICS. 



case, and possess, in general, nearly three times the amount of 

 force requisite for this purpose. 



The weight of muscle in the virgin uterus is about, one 

 and a half ounces, and this muscle is increased to one and a 

 half pounds during pregnancy ; that is, it is increased about 

 sixteen fold. If ever there was a muscular system produced 

 to effect a specific object, the uterine muscle maybe regarded 

 as such ; and if the principle of least action in nature be valid, 

 we should expect such a muscle to be developed only to the 

 extent required, and not beyond it. Considered from this 

 point of view, the preceding calculation must be regarded as 

 interesting ; for it shows that the uterine muscle possesses a 

 force of 3.4 lbs., intended to overcome a maximum resistance 

 of 3.1 lbs. It would be a waste of power to endow the uterus 

 with more force than I have shown it to possess, for it is not 

 necessary that the uterus should complete the second stage of 

 labour, as the abdominal muscles are available for this pur- 

 pose ; so that by using them, and not giving the uterus more 

 force than is absolutely necessary for the first stage of labour, 

 an admirable economy of muscular power is effected. 



Viewed in connexion with the doctrine of Final Causes, the 

 uterine muscle presents a subject well worthy of contemplation. 

 It is plainly necessary that the first stage in the expulsion of 

 the foetus should not be entrusted to a voluntary muscle, and 

 hence an involuntary muscle is gradually provided, which 

 takes the initiative, and commences the process of parturition, 

 the completion of which is then accomplished by the aid of 

 voluntary muscles, to the employment of which, at this stage, 

 no moral objection can be raised. It is also necessary (if the 

 Contriver be all-wise, or if the principle of Least Action in 

 nature be true), that the involuntary muscle, so produced, 

 should not possess more or less force than is requisite for its 

 purpose. The uterine muscle does not grow, to meet a grow- 



