122 EIGHTH REPORT 1838. 



originate from raucous membrane, that the permanent teeth have no 

 connexion with the deciduous set, and that the sac and pulps must be 

 referred to the class of organs denominated bulbs. He anticipates the 

 discovery of the follicular stage in the dentition of all animals, and if 

 so, that it will explain the varying and complicated forms of the pulp 

 and sacs. 



Experiments and Observations on the Cause of the Sounds of Respiration. 

 By Dr. Spittal. 



The object of this communication was to show that the theory of 

 Laennec, in regard to the cause of the respiratory sounds, — viz. that 

 all those known by the terms vesicular, bronchial, tracheal, as well as 

 cavernous and amphoric respiratory murmurs, are caused by the fric- 

 tion of the air against the parietes of the air cells, bronchial tubes, tra- 

 chea, and of cavities of different dimensions, — has never been proved ; 

 that the few experiments which have been advanced in support of 

 it, are far from establishing the conclusions which have been deduced 

 from them ; and that it is highly probable that, according to the theory 

 of M. Beau*, these sounds either owe their existence to, or are in part 

 produced or modified by, the transmission or reverberation of a sound 

 which takes place in the superior respiratory passages, and which has 

 been termed by M. Beau the "guttural" respiratory sound. In sup- 

 port of the first theoiy, it was observed, that the best and almost the 

 only experiment was that of Magendie, in which air was blown into 

 the lungs by means of a pair of bellows, and sounds, resembling 

 the respiratory murmur, were perceived ; from which M. Magendie 

 drew the conclusion, that because air passed to and from the lungs 

 during this experiment, as well as during respiration, therefore the re- 

 spiratory sounds are produced by the friction of the air against the pa- 

 rietes of the bronchial tubes and air cells of the lungs. It was stated 

 that the similarity between the sound produced by a pair of bellows 

 and the guttural sound was admitted by Laennec ; and that it was also 

 observed that a similar sound could be produced by blowing air through 

 almost any tube ; differing in tone and degree according to the diame- 

 ter or shape of the opening in the tube, the force with which the air 

 is made to issue from it, and the nature of the materials of which it is 

 composed. The experiments of M. Beau, in support of his particular 

 theory, it was noticed, were open to objections, and did not seem to 

 bear out very clearly the conclusions at which he arrives ; which may 

 perhaps account for the neglect his view of the subject has met with. 

 For the purpose of obviating these difficulties, and showing in a more 

 distinct manner the probable truth of this theory, to a certain extent at 

 least, several experiments were devised by Dr. Spittal. In these ex- 

 pei'iments wo sti'eatn of air was allowed to pass through those parts 

 which were the subject of observation ; they were only allowed to be- 

 come, and remain, distended with air; while, at the same time, the 



* Archives Generales, Paris, 1834. 



