468 OF GENERATION AND DEVELOPMENT. 



sired effect. The efficacy of these means, the latter in particular, 

 obviously depends upon the influence" of the spinal cord and its nerves 

 upon the muscular fibres of the uterus ; the application of cold to the 

 surface, or the irritation of the nipple, occasioning a reflex action in 

 the uterus. But it is probable that this organ has also considerable power 

 of contracting, independently of the nervous system ; thus there are 

 well-authenticated cases on record, in which the foetus has been expelled 

 after the somatic death ( 65) of the parent ; which must have been in 

 consequence of the persistence of the independent contractility of the 

 Uterus, and the relaxed state of all the parts through which the child 

 had to make its exit. 



829. The cause of the occasional occurrence of the parturient efforts 

 at an unusually early period, is as little understood as that of their ordi- 

 nary action. There are some individuals, in whom this regularly happens 

 at a certain month ; so that it seems to be an action natural to them. 

 In many cases, however, it may be traced to some undue exertion of 

 body, or mental excitement ; and not unfrequently to a general constitu- 

 tional irritability, which renders the system liable to be deranged by 

 very trifling causes. Premature labour is always to be prevented, if 

 possible, being injurious alike to both mother and child ; and for this pre- 

 vention we have chiefly to rely upon rest and tranquillity of mind and 

 body, and upon the careful avoidance of all those exciting causes, which 

 are liable to produce uterine contractions by their operation upon the 

 nervous system ; whilst, at the same time, any measures which will in- 

 vigorate the body, without stimulating it, should not be overlooked. 



830. A peculiar preparation is made, in the females of the class Mam- 

 malia, for the sustenance of the infant during a long period after birth. 

 This consists in the secretion of a fluid, from the glands termed Mam- 

 mary, which contains all the elements that are required for the develop- 

 ment of the body of the infant, during the first year. These glands 

 present themselves in an almost rudimentary state, in some of the non- 



placental animals of the class ; consisting only of 

 Fig. 151. a f ew l ar g e follicles, which open separately upon 



the surface (Fig. 110). In the higher Mammalia, 

 how ever, we find it composed of vast numbers of 

 minute follicles, clustered together upon excre- 

 tory ducts. The general arrangement of these, 

 in the human subject, is seen in Fig. 151 ; and in 

 Fig. 115, the character of the follicles thein- 

 , selves, and of the secreting epithelial cells they 



Termination of portion of .' , 11-1 * 



milk-duct in follicles; from a contain, as seen under a much higher magnifying 



mercurial injection, bv Sir A 11 -111 TI i TV ir 



Cooper ; enlarged four times. ' power, has been already shown. Jiacn Mammary 

 gland consists of a number of glandulae, which 



are held together by areolar and fibrous tissue ; this arrangement may 

 probably have reference to the mobility, which it is requisite that the 

 different parts of the mass should possess, one upon the other, in con- 

 sequence of its situation upon the pectoralis muscle. The ducts con- 

 verge and unite together ; so as at last to form ten or twelve principal 

 trunks, which terminate in the nipple. At the base of the nipple, these 

 tubes dilate into reservoirs, which extend beneath the areola, and to 



