375 



of caloric and of renewing the processes of secretion. In like manner 

 the power of contraction, inherent in the muscular fibre, survives the 

 destruction of both the sensorial and nervous powers, having an ex- 

 istence independent of either, although in the entire state of the 

 functions they are subjected to the entire influence of both. 



A difficulty here presents itself. If both the nervous and muscular 

 powers be independent of the sensorial power, why, it may be asked, 

 do the more perfect animals survive for so short a time the loss of the 

 sensorial functions ? This the author explains by the dependence of 

 respiration on all the three powers, the sensorial, nervous, and mus- 

 cular, and its consequent cessation when either of these powers is 

 withdrawn. In support of this view of the subject, he adduces va- 

 rious arguments to show that the muscles of respiration belong to the 

 class of voluntary muscles, and that their action in performing that 

 function is strictly voluntary, and the result of an impression made 

 upon the sensorium by the want of fresh air in the lungs. These 

 actions, though they have become automatic, are originally and es- 

 sentially voluntary, and remain so even during apoplexy, as long as 

 the breathing continues ; but as soon as all sensibility is destroyed 

 they necessarily cease, and death ensues. The phenomena are not 

 explicable upon the hypothesis of a particular sympathy existing in 

 the nerves distributed to the muscles subservient to respiration, and, 

 if the above theory be adopted, require no other supposition for their 

 explanation. As the organs supplied by the ganglionic nerves are 

 subjected to the influence, not of any one but of every part of the 

 brain and spinal cord, no inference respecting the sympathies of any 

 of these nerves can be drawn, either from their particular origin or 

 mode of distribution ; and still less room can there be for such infe- 

 rences in functions, where, as in respiration, the sensorial power is 

 so materially concerned. 



On the Respiration of Birds. By William Allen and William Hasle- 

 dine Pepys, Esqrs. Fellows of the Royal Society. Read April 30, 

 1829. [Phil. Trans. 1829, p. 279.] 



The inquiries of the authors on human respiration, and on that of 

 the guinea pig, and of which they communicated the details to the 

 Royal Society in former papers, are here extended to the respiration 

 of birds. Pigeons were the subjects of these experiments, and the 

 same apparatus was employed as the one used for the guinea pig, 

 described in the Philosophical Transactions for 1809. 



The object of the first experiment was to ascertain the changes 

 which take place in atmospheric air when breathed by a bird in the 

 most natural manner. For this purpose a pigeon was placed in a 

 glass vessel containing 62 cubic inches of air, and communicating 

 with two gasometers, one of which supplied from time to time fresh 

 quantities of air, and the other received portions which become vitiated 

 by respiration. The experiment lasted 69 minutes, and was produc- 

 tive of no injury to the bird excepting a slight appearance of uneasi- 



