CONTENTS OF THE LAEGE INTESTINE. 395 



the bile, and in part to matters secreted by the mucous 

 membrane of the colon and the glands near the anus. 



The entire quantity of faeces in the twenty-four hours 

 was found by Wehsarg to be about 4'6 ounces. This was 

 the mean of seventeen observations ; the largest quantity 

 being 10*8 ounces, and "the smallest 2'4 ounces. 1 As the 

 average of five examinations of his own faeces on successive 

 days, Dr. Hammond found the entire quantity in the twenty- 

 four hours to be about 5*24 ounces. 2 



The reaction of the faeces is undoubtedly very variable, 

 depending chiefly upon the character of the food. Marcet 

 found the human excrements always alkaline. 3 Wehsarg, 

 on the other hand, found the reaction generally acid, but 

 very frequently alkaline or neutral. 



The first accurate analyses of the faeces were made by 

 Berzelius ; but the great advances which have been made in 

 physiological chemistry since that time have enabled later 

 observers to arrive at results much more definite and satis- 

 factory. The recent researches into the composition of the 

 healthy faeces by "Wehsarg, already referred to, have thrown 

 much light upon the nature of the constituents derived from 

 the food and the bile, as well as. the proportions of the va- 

 rious inorganic salts. Marcet has lately discovered a crys- 

 tallizable substance peculiar to the human faeces ; 4 and we 

 have recently shown that probably the most important excre- 

 mentitious principle discharged by the rectum is derived 



1 Op. tit., p. 62. 



2 HAMMOND, Experimental Researches relative to the Nutritive Value of Albu- 

 men, Starch, and Gum, when singly and exclusively used as Food, Philadelphia, 

 1857, p. 18. 



3 MARCET, An Account of the Organic Chemical Constituents or Immediate 

 Principles of the Excrements of Man and Animals in the Healthy Slate. Philo- 

 sophical Transactions, London, 1854, p. 265. 



4 MARCET, An Account of the Organic Chemical Constituents or Immediate 

 Principles of the Excrements of Man and Animals in the Healthy State. Philo- 

 sophical Transactions, -London, 1854, p. 265 et seq. ; and, On the Immediate Prin- 

 ciples of the Human Excrements in the Healthy State. Idem., 1857, p. 403 ct seq. 



