262 SIXTH REPORT — 1836. 



to isolate or at least to bring sufficiently into relief the essen- 

 tial cause or causes of each sound. To the execution of the 

 plan of experimental inquiry thus glanced at, the Committee 

 have devoted some time during the summer, in the course 

 of which they have had to encounter numerous difficulties, 

 especially from the want of sure means of destroying the sensi- 

 bility of the animal, without suspending or greatly impairing 

 the action of the heart. And in this respect they have been 

 much less fortunate than several preceding experimentalists, 

 having in no one of the numerous subjects on which they have 

 operated, been able to continue their observations for a longer 

 period than forty-five minutes, notwithstanding the utmost care 

 to avoid unnecessary loss of blood and to maintain artificial 

 respiration. It is proper to add, that the subjects of these ob- 

 servations were in most instances young asses from three to six 

 months old, in apparently good health, and that the mode of 

 preparation was in a few instances poisoning with woorara, in 

 others stunning by a blow on the head, but in a majority of 

 the experiments the animal was pithed. Other animals were 

 tried as well as young asses, viz. the horse, the dog, and the 

 domestic fowl ; but for various reasons these trials were not 

 attended ^vith results recommending their repetition. 



The Committee consider the most convenient order in which 

 to state the facts in their possession, and their inferences from 

 those facts, to be, to describe first succinctly, and from the origi- 

 nal notes taken on the spot, such of their experiments as gave 

 available results; then briefly to arrange, under the head of each 

 supposed or possible cause, such points in the experiments as 

 may seem to the Committee to make decidedly in favour of or 

 against the claims of each of such possible causes ; and lastlj-, 

 to give a summary of the conclusions which the Committee 

 have adopted from the whole of their inquiries. 



Memoranda of Experiments, &)C. — ^The Committee made 

 some observations in the first instance on their own persons. 

 To satisfy themselves fully as to how far the sounds might be 

 modified by circumstances, such as the state of the lungs, 

 whether distended or collapsed ; the state of the circulation, 

 whether excited or tranquil ; and the position of the body ; the 

 Committee examined the heart in their own persons under all 

 those varieties of circumstance, and found, that when the sub- 

 ject of observation is supine or leaning a little backwards to- 

 wards the right side, the first sound is uniform, dull, and ^vith- 

 out any easily perceptible impulse ; but the subject leaning 

 forwards, and especiaJly if inclining much to the left side, the 



