68 AGE. 



glands, are in a state of high development, out observing that the fibres of the stomach 



as indicated both by their size and by their and intestines in infancy and childhood are, 



tendency to disease. The stomach and duo- like those of the heart and other involuntary 



denum are fully formed, but the sensibility muscles, more irritable than in after life ; hence 



of their mucous membrane is adapted only to the contents of these viscera are propelled more 



the milk of the mother; any other kind of rapidly, and the evacuations are more frequent; 



food has a greater or less tendency to produce their tissue is also softer, and their colour more 



irritation. This membrane is thick, extremely approaching to white. 



villous and vascular, and consequently of a The liver undergoes a great change after 



rose-colour.* In young persons it assumes birth both in form and in function. The pecu- 



a milky or satin-like appearance; in the adult liar circulation of which it formed so important 



it becomes slightly ash-coloured, especially in an organ during fcetal life being abolished, 



the duodenum and in the commencement of the left lobe which nearly equalled the right 



the ileum ; in the old subject it is more de- in volume, is diminished to a third of its original 



cidedlyashy. Its whitish appearance, according size. But while the umbilical vein and the 



to Andral,f is found either in very old persons canalis venosus are obliterated, the vena portae 



or in younger subjects who have died of ma- is developed, and the bilious secretion becomes 



rasmus. In the adult the small intestines, the predominant function. Of the further 



according to Orfila,| bear a proportion of eight changes which this organ experiences, we have 



to one as compared with the distance from the very little knowledge, except that the whole 



mouth to the anus ; in the infant the proper- bulk is greatly lessened, and that the colour of 



tion is no less than twelve to one. The large its parenchyma becomes darker, and that it is 



intestines are longer with respect to the small more subject to disease in after periods. Oc- 



intestines in the infant than in the adult; but their casionally we meet with instances in which the 



calibre is proportionally smaller. Ascending to fetal proportions of the liver continue through 



the mouth we might be tempted to say that life (Andral). The bile has not been carefully 



there is evidence of incompleteness in the ab- examined with reference to particular ages, 



sence of teeth; but a moment's consideration but it is known to be less viscid and to contain 



assures us that the organs collected in this part a smaller quantity of its peculiar principles 



are all eminently adapted to their function, in infancy ; while its greater liability to con- 



The food is already prepared by the mother, cretions at more advanced periods indicates an 



and only needs to be extracted and conveyed alteration in its composition. The gall-blad- 



into the pharynx ; actions which are perfectly der, though small at birth, contains bile, green 



achieved by the lips, cheeks, and tongue, in colour and bitter in taste, and soon becomes 



When the period has arrived at which this enlarged. 



food can no longer be furnished with safety The spleen also increases in volume, but 

 to the mother, and when all the purposes are what alteration takes place in the progress 

 accomplished which were intended in this to maturity, in its function, must, of course, be 

 close connexion between the two beings doubtful until the function itself be better 

 purposes in all probability of a moral as well understood . Probably its enlargement is con- 

 as a physical character the infant is prepared nected with the distended condition of the 

 for a more independent existence by the emer- venous system. Of the changes in the pan- 

 gence of teeth. This event generally begins creas and salivary glands, we know little more 

 about the sixth or seventh month by the appear- than that their texture increases in firmness. 

 ance of the two middle incisors in the lower The lacteals, lymphatics, and their respective 

 jaw ; these are followed by the corresponding ganglions have a very marked development, 

 teeth in the upper jaw ; next are seen the It is to be regretted that no observations have 

 lateral incisors below and above : the rest as yet been made upon the composition of the 

 appear in the following order; the first molars, chyle at different ages. There are doubtless 

 the canines, and the second molars ; those of many alterations corresponding to the varying 

 the lower jaw having generally the priority activity of the digestive function, and to the 

 of emergence. The milk-teeth, as they are kinds of aliment used at those periods, 

 called, by the end of the seventh year have So much for the organs and functions which 

 given way to the second and permanent series, are concerned in augmenting or modifying the 

 For the different characters of the two sets, nutrient matter. Before proceeding to those 

 the order of their appearance, and other par- of the relative life, we must allude to the 

 ticulars, we beg to refer the reader to the organs of excretion. The kidneys at birth 

 article TEETH. That the first series should have not lost the traces of their tabular forma- 

 be only temporary is a necessary provision, tion, but these are soon effaced. The weight 

 in conformity with the change in the conforma- of these organs at birth is to that of the whole 

 tion of the maxillary bones which ensues at body as 1-80; in the adult 1-240. The me- 

 the same time. dullary portion is more abundant than the corti- 

 We must not leave the alimentary tract with- cal in early life. The supra-renal capsules soon be- 

 gin to shrink from their foetal size. The ureters 



Billard^Traite des Maladies des Enfans, &c. are large, and the bladder has a more elongated 



Precis d'Anat. Pathol. f orm tnan in a f ter p er i oc j s it also occupies a 



I Lecons de Med. Leg. t. i. p. o2. i v , L , . rpi f f 



This statement is at variance with that of hl g he 1 r situation above the pelvis. The func- 



Meckel, who says that the small intestine is much tlonal qualities of these forms are not so wel 



shorter in the early periods. Op. cit. t. iii. p. 424. ascertained as the analogy of their organization to 



