CHEMISTRY AND TOXICOLOGY OF MUSHROOMS. 291 



age of twelve edible species gave 7 -per cent, ash in the stem and 

 8.96 per cent, in the cap. 



In regard to the constituents of the ash, potassium is by far the 

 most abundant the oxide averaging about 50 per cent, of the total 

 ash. Phosphoric acid stands next to potassium in abundance and 

 importance, constituting, on an average, about one-third of the entire 

 ash. Oxides of manganese and iron are always present ; the former 

 averaging about 3 per cent, and the latter 5 per cent, to 2 per cent, 

 of the ash. Sodium, calcium, and chlorine are usually present in 

 small and varying quantities. Sulphuric acid occurs in the ash of all 

 fungi, and is remarkable for the great variation in quantity present 

 in different species ; e. g., ash of Helvetia esculenta contains 1.58 per 

 cent. H2 SO4 while that of Agaricus campestris contains the relatively 

 enormous amount of 24.29 per cent. 



Any discussion of the bare composition of a food is necessarily 

 incomplete without a consideration of the nutritive value of the various 

 constituents. This is especially desirable in the case of the mush- 

 rooms, for while they are frequently overestimated and occasionally 

 ridiculously overpraised by their friends, they are quite generally 

 distrusted and sometimes held in veritable abhorrence by those who 

 are ignorant of their many excellent qualities. On the one hand, we 

 are told that " gastronomically and chemically considered the flesh 

 of the mushroom has been proven to be almost identical with meat, 

 and possesses the same nourishing properties." We frequently hear 

 them referred to as ** vegetable beefsteak," " manna of the poor," 

 and other equally extravagant and misleading terms. On the other 

 hand, we see vast quantities of the most delicious food rotting in the 

 fields and woods because they are regarded by the vast majority of 

 the people as "toad-stools" and as such particularly repulsive and 

 poisonous. 



Foods may be divided into three classes according to the functions 

 they perform : 



{a) To form the material of the body and repair its wastes. 



(J)) To supply energy for muscular exertion and for the main- 

 tenance of the body heat. 



(c) Relishes. 



The formation of the body material and the repair of its wastes 

 is the function of the proteids of foods. It has been found by care- 

 ful experiment that a man at moderately hard muscular exertion 

 requires .28 lb. of digestible proteids daily. The chief sources of our 

 proteid foods are meats, fish, beans, etc. It has been as a proteid 

 food that mushrooms have been most strongly recommended. Refer- 



