339 CRITICAL NOTICES OF NEW PUBLICATIONS. 



phere ; and it is possible that it may, on philosophical principles, be consider- 

 ed as a prognosticator of atmospheric changes, since the agent itself has an 

 evident connection with many meteorological effects, which we at present 

 find some difficulty in explaining. 



We take our farewell of Mr. Higgins, earnestly recommending 

 his book to the perusal of our readers ; nor will the ladies refuse so 

 grave a subject as philosophy a place in their boudoirs^ when it is 

 so elegantly arrayed. 



A Majiiial of Entomolosy, from the German of Dr. H. Burmeister, 

 by W. E. Shuckard, M. E. S. London : Edward Churton. 



The publication of this admirable work is now drawing to a close, 

 and we would strongly advise every one who takes a delight 

 in the pursuit of this branch of Natural History, to procure a copy. 

 The mechanism by which atmospheric air is admitted to the inter- 

 nal organs of respiration, is described in so clear and skilful a man- 

 mer as to be highly interesting, not only to the professed entomolo- 

 gist, but to the most casual observer of nature. From the experi- 

 ments of Sorg, Hausmann, and others, upon the decomposition of 

 air during the respiration of insects, it is ascertained that " all 

 breathing insects deprive the air of a considerable portion of its oxy- 

 gen, and give off, in lieu of it, carbonic acid ;" the quantity of oxy- 

 gen withdrawn by breathing, and the quantity of carbonic acid giv- 

 en off, varying according to the size of the creature, and the inten- 

 sity of its respiration. The chapters on " The metamorphosis — 

 muscular motion — the emission of sound — instinct — and self-pre- 

 servation of insects," are replete with valuable information, and can- 

 not fail exciting the most lively interest in the mind of every physio- 

 logical student. 



A Practical Treatise on the Diseases of the Teeth, in which the ori~ 

 gin and nature of Decay are explained, and the means of Preveyi^ 

 tion pointed out. By W. Robertson. London : Longman & Co. 

 1835. pp. 158. 



The chief object of the author in presenting the present volume 

 to the public, is, to make non-professional readers acquainted with 

 the nature and progress of caries, or decay of the teeth, by placing 

 before them new views of the origin of the disease, different, and, 

 indeed, altogether opposed, to the commonly-received opinions on 

 the subject. Mr. Robertson founds his new theory of caries upon 

 the peculiarities of the different classes of the teeth, upon the indivi- 

 dual anatomical structure of particular teeth, and, also, upon the 

 organization of the enamel and proper bone of the tooth, which, not 

 being strictly analogous in its structure to the other parts of the 

 osseous system, does not bear a perfect resemblance to them in its 

 diseases. Objecting to the theories of Bell and Fox, as insufficient 

 to explain the cause of caries, Mr. Robertson advances the opinion 



