quoted by the Reviewer, occurs in the Section entitled *' General 

 Considerations ;" and the principle is expressly applied to Plants as 

 well as to Animals. In the Section on Respiration in Plants, a dis- 

 tinction is made between their true respiration (which io shown to 

 be analogous to that of Animals), and the fixation of carbon from 

 the atmosphere, which is characterised as a process of a different 

 nature, independent, so far as is known, of mere physical laws. 



The Reviewer then finds fault with the principle itself; being 

 evidently ignorant that it has been recognised by most of the recent 

 physiological writers. Professor Miiller, for example, thus expresses 

 himself : — " The interchange of the carbonic acid and oxygen in the 

 lungs is wholly in accordance with the physical laws of the absorp- 

 tion of gases." — (Translation by Baly, vol. 1, p. 340). A little 

 afterwards the Reviewer states as a fact " that the oxygen consumed 

 is, as nearly as can be estimated, in the exact ratio of the carbonic 

 acid thrown out." This might have passed very well twenty years 

 ago ; but every student now knows that the Reviewer's position has 

 been long since overthrown ; the independent experiments of Ber- 

 thollet, Despretz, Dulong, Edwards, Collard de Martigny, Miiller, 

 and others, having united in proving that much more oxygen dis- 

 appears than is contained in the carbonic acid of the expired air. 

 Even Allen and Pepys, the only experimenters whose results can be 

 opposed to these, noticed a considerable disappearance of oxygen in 

 some of their experiments ; but they set it down as accidental. 



I trust that I have now sufficiently vindicated myself from the 

 principal charges which the Reviewer has brought against me ; and 

 that I have proved his incompetency to pronounce an opinion upon 

 the merits of my work. More than this it is not my desire to urge. 

 And I shall conclude with again expressing my regret, at the neces- 

 sity I have felt to make animadversions that so seriously affect the 

 character of a Journal, which has rendered great services to Medical 

 Science, and to which the Profession has been accustomed to look 

 up with respect. 



In justice to myself, I think it right to add the following con- 

 firmatory testimony from individuals whose authority on Theological 

 questions, and in General Science, will give additional weight to 

 my own statements. To all of these gentlemen the above Remarks 

 have been submitted ; and my only reason for not printing their 

 replies in full, is that I am anxious to present them to the reader 

 in the narrowest possible compass. 



From the Rev. J. Pye Smith, D.D., Theological Tutor at Homerton 

 Academy^ to Lant Carpenter, LL.D. 

 " As soon as I saw an account in the Athenceum of Dr. William Car- 

 penter's Principles of Physiology, I ordered it of my bookseller. Had I 

 not been, for more than five months, and were I not still, under the 

 pressure of proximate duties, heavily augmented by the unexpected re- 

 signation of my theological colleague, I should have applied myself to the 

 study of the work : I may say, I should have assiduously devoted myself 

 to it, so far as necessary engagements would have permitted. I saw it to 

 be such a book as I had long wished to see, and for many years had en- 

 deavoured to supply for myself, in a sort of composite manner, by adding 

 book to book, and combining what I could learn from each in my own 

 imperfect way of mental association. The plan of this volume at once 

 attracted me ; and I expected to find it the long- sought desideratum. 

 It would be absurd for me to set myself up as qualified to sit in judgment 



