ASSIMILATION AND NUTRITION. 



poured forth, for the purpose of filling up the hollow, and producing a 

 rupture of the skin ; but >ve know to a certainty that some such general 

 process is in most cases absolutely necessary ; we know that such a 

 rupture must take place in the natural mode of cure ; that the atmos- 

 phere must come into close contact with the mouths of the restorative 

 secernents ; that a milder or softer fluid could not possibly be secreted for 

 such a purpose ; and that the entire process exhibits proofs of most admi- 

 rable skill and sagacity. It is at times possible for us to assist the process 

 by the lancet, which accelerates the opening. Yet even in this case we do 

 no more than assist it, and are only, as we ought ever to be in all similar 

 cases, bumble coadjutors and imitators of nature, and admirers of that 

 all-perfect and ever-present wisdom which we are so often called upon to 

 witness, but are never capable of rivalling. 



A process closely similar to this is perpetually unfolding in vegetable life. 

 And it was merely by taking advantage of this process that Mr. Forsythe 

 was able to make old, but well-rooted, stumps of fruit-trees throw forth, 

 far more rapidly than he could saplings, a thrifty family of vigorous and 

 well-bearing shoots : for the compost for which he was so celebrated 

 does nothing more than merely increase the secernent and absorbent 

 action of the vegetable frame by its stimulating property, and defend the 

 wounded part to which it is apphed fi-om being injured by the inclemency 

 of the weather. 



From what has thus far been observed it appears obvious that all the 

 different parts of the living body are assimilating organs, or, in other 

 words, are capable of converting the common nutriment of the blood into 

 their own respective natures, and for their own respective uses. And it 

 has also appeared, that under particular circumstances every part is capa- 

 ble, moreover, of secreting a material different from that of its owii 

 nature, as, for example, the material of pus, whenever such a substance 

 is necessary. 



This view of the subject will lead us to understand with facility how it 

 is possible for various organs of the system to maintain two distinct secre- 

 tions at the same time : one of a matter similar to its own substance, 

 and exclusively for its own use ; and another of a matter distinct from its 

 own substance, and in many instances subservient to the system in general. 



Of this last kind are the stomach, the liver, the respiratory organ,' and 

 the brain : each of which secretes, independently of the matter for its 

 own nourishment, a matter absolutely necessary to the health and perfec- 

 tion of the general machine ; as the gastric juice, the curious and won- 

 derful properties of which I described on a former occasion ; the oxyge- 

 nous principle of the inspired air, and, as some suppose, those of light or 

 caloric ; the bile ; and the nervous fluid, or material of sensation. 



There are various other organs of a smaller kind, and simpler texture, 

 which also perform the same double oflice, and secrete materials of a 

 much more local use, or which are intended to be altogether thrown away 

 from the system, as waste or noxious bodies. And to the one or the 

 other of these classes belong the kidneys, the intestinal tube, the minute 

 and very simple perspiratory follicles of the skin, the delicate organs that 

 separate the sahvaand mucus that serve to lubricate the mouth and nostrils, 

 and those that elaborate the tears, the wax of the inner ear, and the fat. 



The organs, of whatever size or texture, that perform this double func- 

 tion, are called secretory glands ; and they are distinguished into different; 

 sots, either from their peculiar oflice or peculiar structure ; as salivary. 



