532 
Bottomley . — The Significance of Certain 
Rothamsted soil. 
Soil plus sterilized bacterized peat (a) 0*367 grm. N per 100 grm. soil. 
(*) °* 3 6 3 
Soil plus active bacterized peat (a) 0*421 „ „ 
(^ 0*417 
An average gain of 54 mg. of N per 100 grm. soil. 
It was also found ( 3 ) that an aqueous extract of the bacterized peat 
(one part peat to 200 partswater) supplied all the plant food necessary 
for water-cultures with tomato, barley, and buck-wheat seedlings. 
Experiments conducted at Kew Gardens and Chelsea Physic Garden 
during the summer of last year (1913) on various pot plants — wheat, barley, 
oats, maize, salvia, fuchsia, carnation, primula, &c. — demonstrated that the 
bacterized peat possessed a certain growth-stimulating property which 
could not be accounted for by any known manurial constituents present ( 4 ). 
Further experiments showed that this stimulating substance was soluble in 
water and effective in very minute quantities. Dr. Rosenheim, in an experi- 
ment with seedlings of Primula malacoides potted up in loam, leaf mould, 
and sand, found that plants watered twice with the water extract of only 
o*i 8 grm. of bacterized peat were, after six weeks’ growth, double the size 
of similar untreated plants, and it was noted that flower production and 
root development were promoted equally with increase of foliage. 
These results suggested that the growth-stimulating action of the 
bacterized peat might be due to the presence of substances similar in nature 
to the accessory food bodies concerned in animal nutrition. 
Recent work on animal metabolism has shown that animals cannot live 
on a diet of pure proteins, carbohydrates, fats, and inorganic salts alone. 
In addition very small amounts of certain other organic compounds, the 
so-called accessory food bodies, are absolutely essential for normal nutrition 
and growth. 
These substances were first recognized in connexion with the diseases 
of beri-beri and scurvy, which are caused by a deficiency in diet of minute 
amounts of certain nitrogenous substances necessary for normal metabolism. 
They have been obtained chiefly from vegetable tissues — rice polishings, 
wheat, barley, lentils, yeast, fresh vegetables, and fruits ; amongst animal 
tissues from milk, egg-yolk, and ox brain. 
More recently the researches of Osborn and Mendel ( 5 ) and Hopkins (6) 
have demonstrated the importance of small amounts of similar accessory 
food substances in the metabolism of growing animals. These investigators 
have shown that young rats fed on a dietary consisting of a mixture of pure 
proteins, carbohydrates, fats, and inorganic salts failed to grow, but on the 
addition of a very small amount of certain substances obtained from milk 
growth was normal. 
