22 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



of certain organic compounds containing nitrogen — namely proteids 

 and albuminoids ; and others which are non-nitrogenous — to wit, fats 

 and carbohydrates. Inorganic bodies are present in the shape of 

 various mineral salts and water. Inasmuch as proteids, acting 

 with salts and water, are the tissue-formers and are also energy 

 providers, they are the only indispensable ingredients of a diet. Fats 

 and carbohydrates, while they can both be stored in the body for 

 an indefinite time, can only supply energy. 



In judging of the usefulness or otherwise of a certain substance 

 as food, it is not sufficient to know what quantities of fat, proteid, 

 &c, it contains, but how much of these food elements can be absorbed. 

 Absorption depends upon many factors ; solubility in the digestive 

 juices, the smell, taste and appearance of the food, and the condition 

 of the body at the time of ingestion — all exercise an important in- 

 fluence. Violent exercise will hinder absorption, and too ample a meal 

 will also considerably reduce it. 



It has been found that proteids are the least completely absorbed 

 of the three great food elements. On a purely vegetable diet the 

 loss may be very great indeed, amounting in the case of carrots, 

 for example, to nearly 40 per cent, of the total proteid consumed 

 (Hutchinson). 



The fats are more completely absorbed than proteids, but the 

 absorption of carbohydrates is the most perfect of all. 



It is worthy of note that there is least loss on absorption when a 

 mixed diet is taken. 



Besides its essential constituents, a food commonly contains a 

 certain amount of indigestible matter. This, contrary to what 

 might be thought, is by no means useless. It forms bulk or ballast, 

 which by its merely mechanical effect stimulates intestinal action. 

 This fact is taken due advantage of in drawing up a dietary in con- 

 ditions in which intestinal inactivity is a prominent symptom. 



And again, no discourse on food values could be complete without 

 some reference to those curious chemical bodies called Vitamines. 

 First discovered by Funk during his investigations into the cause 

 of Beri-beri, they have called forth a great amount of research the 

 last few years. 



Funk found that when fowls were fed on polished rice they 

 developed Beri-beri in from one to six weeks and died in a few days 

 after the onset of the disease. However, if an extract of rice polishings 

 was injected into the circulation, the birds recovered magically in 

 a few hours. Thus it was evident that a substance was present in 

 the pericarp of the rice grain which, when removed from the diet 

 allowed the disease to occur, but which was capable of curing the 

 disease although thp latter was fully developed. He isolated this 

 body and named it " Vitamine." The quantity in any food is 

 extremely minute, only 6-i6 grains being obtained from no lb. of 

 rice pericarps. Assuming the pericarp to weigh from one-sixth to 

 one-tenth of the complete grain, we find that an amount of rice approxi- 



