CRITICAL NOTICES OF NEW PUBLICATIONS. 339 



be observed before and after eating ; drinks ; the proper regulation 

 of the bowels. This list necessarily leads us to infer that Dr. Combe's 

 pages embrace a great diversity of investigation, bearing directly and 

 strongly on the health, and consequently on the happiness of man- 

 kind. We greatly admire his method of communicating physiological 

 and practical knowledge, and would gladly enhance the value of this 

 article, by drawing largely on the Doctor's rich stores of erudition 

 and well digested experience : but, on this occasion, our limits pre- 

 clude us from attempting more than the introduction of a few desultory 

 sketches, as inducements to a careful and repeated study of the 

 '* Physiology of Digestion and the Principles of DieteticSj" as sub- 

 jects essentially conducive to the conservation of health and the 

 prevention of disease. 



By reflection on numerous authentic facts. Dr. C, establishes the 

 induction — that, in every department of nature, expenditure of 

 material is inseparable from action ; and that, in living bodies, 

 waste goes on so rapidly and by so many different channels, that 

 life could not be maintained for any length of time without an ex- 

 press provision being made for compensating its occurrence. Where- 

 fore, in surveying the respective modes of existence of vegetables and 

 animals, with a view of ascertaining by what means this compensa- 

 tion is effected, the first striking difference between them which we 

 perceive, is the fixity of position of the one, and the free locomotive 

 power of the other. The vegetable grows, flourishes, and dies fixed 

 to the same spot of earth from which it sprang ; and, however exter- 

 nal circumstances may change around it, it must remain and submit 

 to their influence. If the earth to which its roots are attached be 

 removed, if it be deprived of moisture, and solar heat, and light, it 

 cannot go in search of them, but must remain to droop and to 

 perish. But it is otherwise with animals. These not only enjoy 

 the privilege of locomotion, but are compelled to use it, in search of 

 food and shelter ; consequently, if their vessels of nutrition were 

 like those of vegetables, in direct communication with external 

 substances, they would be torn asunder at every movement, and the 

 animals themselves exposed either to die from starvation, or to 

 forego the exercise of the higher functions for which their nature is 

 adapted. But the necessity for a constant change of place being 

 imposed upon them, a different arrangement became indispensable 

 for their nutrition, and the method by which the Creator has reme- 

 died the inconvenience is no less admirable and simple. To enable 

 them to move about and at the same time to maintain a connexion 

 with their food, He has provided them with a stomach wherein they 

 may store up a supply of materials from which sustenance may be 

 gradually elaborated during a period of several hours. The posses- 

 sion of a receptacle for food is accordingly a characteristic of the 

 animal system as contrasted with that of vegetables ; and it is found 

 even in the lowest orders of zoophytes which, in other respects, are 

 so nearly allied to plants. From the details of this interesting com- 

 parison. Dr. C. seems to confirm and elucidate this proposition — 



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