302 Notices^ respecting New Booh, 



descend very well, alihough. other circnmstaiiccs considered, 

 rathermorc tardily. Now those which have a hhdderhave, 

 in addition, all the organs employed by those which have 

 none, and they can nse them like the others. 



One difficulty which we have sometimes heard started, is 

 to ask how a fish, when it wishes to ascend iVom the bottom 

 of the sea, can find strength to raise up by means oF its sides, 

 or generally of its integuments, the enormous column of 

 water which lies upon it, in order to permit its bladder to 

 dilate. But as this vessel is already, by its compression, in 

 equilibrium with the water which presses it, the least effort 

 is sufficient ; and even this effort, however small, is never- 

 theless necessary, that the fish may only rise a few feet by 

 the means which are common to it with the fishes without 

 bladder ; instantly its bladder, being less compressed, will b<i 

 too much dilated ; and, according to M. Delaroche's own 

 cxperinicnts, it will carry it precipitately upwards, and burst 

 its entrails if it does not speedily close it. This second 

 objection is refuted therefore like the former. 



Thus we think we ought to adhere to the ideas of Borelli, 

 as to the use of the air-vessel of fishes ; but although wc 

 differ in opinion from M. Delarochc on this point, we do 

 not the less regard his Memoir as worthy of approbation, 

 from the great number of new and correct observations 

 which it contains, as to the anatomical structure of the 

 bladder, as well as upon the nature and sources of the air 

 which it contains ; and we have the honour to recommend 

 that it should be printed among the Memoirs of Savam 

 Etravgers. Signed^ 



Lacepedr, Vauquelin, Cuvier. 



M.. 



L. Notices respecting New Books. 



AccuM has just published a ^' MGinial of a Course 

 cf Lectures on Exptrimental Chemistry, and on Mineralogy ; 

 containing^ in the Form of Axioms and concise Outlines, the 

 Elefnenf.s a7id fundamental Truths of chemical and mineral 

 logical Science : intended to illustrate the Lectures on these 

 Branches oj Knowledge in the Theatre of the Surry Institu- 

 tion ; with an Account of the Action of chemical Tests and 

 Modes of applying them in the Practice of the Science,** 



The very full title of this little work fabout 230 pages 

 small ISnio.) sufficiently explains its object. The author 

 states that in wriiinjr it he has endeavoured to exhibit, to 

 the learner, those *^ important facts and fundamental doc- 



trine.'> 



