French Naf,io?ial Listilute, 397 



In speaking of respiration, however, we cannot pass over 

 in silence a memoir read to the Class by M. Provengal, on 

 the respiration of maniinirerte in which the nerves of the 

 eighth pair had been cut, Wc have already spoken of the 

 experinjcnts which had been made to ascertain the influence 

 of these nerves on respiration, by which this influence waS 

 demonstrated : some doubts, however, remained as to the 

 way in which it is exercised. M. Provencal was anxious 

 to ascertain if the animal in which the eighth pair of nerves 

 had been cut, absorbed as much oxygen, and pr(;duced the 

 feame quantity of carbonic acid, before, as afier the opera- 

 tion. Numerous experiments made with care proved that 

 the animal, after th.e' section of the nerves, absoibed Jess 

 oxygen and produced less Carbonic acid than before thij* 

 section ; but these changes are produced by gradation only. 

 At first the rcspirationdties not appear we?»V.ened ; subse- 

 quently, it is effected with less strength ; and finally these 

 phtenomena cease cntirelv, but most probably in . coni=e- 

 quence of the cessation X)f the mechanical functions of the 

 chest. It was iiUeresting to ascertain if the anin^al heat 

 diminished in the same proportions with respiration. M. 

 Provencal therefore made all the experiments necessary for 

 resolving this <]ucstion ; and it would seem that in fact the 

 temperature diminishes soon after the nerves have been cut 

 an<! the respiration has slackened. 



The functions of the organs whose action has been just 

 mentioned, are well known ; but there exists in animals a 

 certain number of other organs whose functions are not 

 evident, and as to the use of which physiologists are still 

 divided in opinion. Among this number, is the swin)ming- 

 bladder of fishes. This singular organ, which is only tfi 

 be found in this class of animals, is not met with in all 

 the species ; and it exhibits so many varieties in its organi- 

 zation, that at the flrst glance one would incline to think 

 that it did not perform the san^e functions in some that it 

 did in others. Generally this bladder is filled with air, and 

 composed of two membranes. Sometimes it communi- 

 cates with the stomach by a canal : at other times it lias 

 no apparent communication, and in this case it contains 

 a peculiar organ of a red colour and of a lamellaicd struc- 

 ture, according to the observations of M. Duvernoy. There 

 are some bladders, however, which are furnished with these 

 red bodies, and which have a canal of commiinicatinn ; and 

 some, but few in number, have peculiar muscles. The opi- 

 nions of authors vary as to the use of tliis organ and oi' n^ 

 difiR.ri.nt parts: in general i, has been thoughl that it was 



employed 



