FCETUS. 



POOD. 



Silnhion of the ancients, from which the later Cyrmaicum, or Ala 

 c/iurw was procured, but Viviani asserts that F. HngctaM does not 

 grow in the country of Cyrene, but only occur* more to the 

 westward. 



ITS. [REPRODCCTIO* IN ANIMALS.] 



I "i M>. The materials taken into the system of organised beings, 

 nncl by which their functions are maintained, and out of which their 

 bodies are formed, are called Food. Food in its widest sense is the 

 raw material out of which plants and animals are manufactured. We 

 shall confine ourselves here to the consideration of the food of animals, 

 and of man in particular. 



Tlie great cause of the necessity of a constant supply of new mutter 

 or food to the body is the waste of the materials of which the blood 

 and organs aro composed, during the performance of their functions. 

 The result of this wnste is seen in the form of the various excretions 

 which are thrown off from the body by the skin, liver, kidneys, and 

 bowels. We shall find, then, that the food, the blood, and the excre- 

 tions, represent each other, that they contain substances of the same 

 nature, and are nil composed of the same ultimate elements. 



If we take a portion of human flesh or blood, and seek for its 

 ultimate elements, we shall find that, on accurate analysis, they will 

 yield the following elements : 



Carbon. 



Hydrogen. 



Nitrogen. 



Oxygen. 



Sulphur. 



Phosphorus. 



Potassium. 



Sodium. 



Calcium. 



Magnesium. 



Iron. 



Manganese. 



Aluminum. 



Copper. 



Chlorine. 



Fluorine. 



Silicon. 



Few or none of these elements occur in the human body in their 

 pure form, but are combined variously with one another, forming 

 compounds having very different physical properties and chemical 

 relations. These elements may be divided, for physiological purposes, 

 into two classes ; the first four, carbon, hydrogen, oxygen, and nitro- 

 gen, being called Organic, whilst the remainder are called Inorganic 

 elements. The first are called organic elements because they are 

 found universally present in plants and animals, and because no animal 

 cell and no vegetable cell can grow unless the whole of these elements 

 exist. Hence, as they lie at the foundation of all organic existence, 

 they are properly designated by this term. 



The inorganic elements, though very generally present in large 

 classes of animals and plants, are not universal Man requires phos- 

 phorus and calcium in the form of phosphate of lime for his bones ; 

 but many of the lower animals contain no phosphate of lime. Sea- 

 animals and plants will not live without chlorine and sodium in the 

 form of common salt ; but fresh-water plants, and plants away from 

 the sea-shorn, do not require this constituent. The term inorganic, 

 then, is applied to these elements to express their different relation 

 to plants and animals, and will also point out their frequent occur- 

 rence in the mineral world. The elements of man's body however 

 are all derived from the mineral world, and are identical with the 

 same bodies in inorganic substances. The carbon found in the human 

 body is identical with that which forms, in its pure state, the diamond 

 which enters into the composition of graphite and various kinds of 

 coal, and is found in limestone and chalk, forming a part of the car- 

 bonic acid of the carbonate of lime, of which these rocks are composed. 

 The hydrogen of the human body is the same as the gas which, united 

 with oxygen, forms water, and when combined with nitrogen pro- 

 duces ammonia. The oxygen of the animal is identical with the gas 

 which, with nitrogen, forms a fifth part of the atmosphere, and which, 

 combined with the metals, forms oxides, of which the greater portion 

 of the earth's surface is composed. The nitrogen of the organic world 

 is identical with that which constitutes BO large a portion of the 

 atmosphere. Nor are these elements alone identical in and out of the 

 human body ; but we find that they possess the same chemical proper- 

 ties, and that their agency in the human body depends on these 

 properties. Thus, carbon and hydrogen are inflammable bodies, and 

 have a great affinity for oxygen, with which they unite, forming car- 

 bonic acid and water, giving out heat during the process of union. 

 This very process goes on In the animal body, and constitutes one of 

 the most important functions of the body. The characteristic features 

 of the functions snd properties of animal and vegetable bodies depend 

 on the chemical relations of the four organic elements. 



These elements never enter the system in their, pure form. Carbon, 

 however needed in the animal frame, cannot be appropriated pure ; 

 and a man would starve with the Koh-i-noor diamond in his mouth, 

 were be not allowed to exchange it for more digestible forms of 

 carbon. The gases hydrogen, oxygen, and nitrogen, would, any one 

 of them in their pure state, destroy human life ; and even when the 

 two last are mixed with the atmosphere, they will not support life in 

 that form. Again, we may mix them in various ways, and not be 

 more miocemful. Carbon combine* with oxygen to form carbonic acid, 

 and hydrogen combines with nitrogen to form ammonia, and these 

 two compounds unite together to form common smelling-salts, or 

 carbonate of ammonia. But xmelling-salU, though they contain all 

 the organic elements, will not serve for human food. Nevertheless 

 what is not food for man is nutriment for plants. Carbonic acid and 

 -'-, supply plant* with materials of growth. It is from these 



two bodies that the vegetable kingdom elaborates all the secretions 

 which give to plants elegance of form, beauty of colour, deliciousness 

 of scent, deadlines* as poisons, and nutritiousness as food. The plant 

 stands between the mineral and animal kingdoms, preparing the former 

 for the service of the latter. Without plants there could be no an 

 In the whole range of natural history we are presented with no 

 instance of an animal existing directly on mineral matter. It in true 

 that many animals are carnivorous, and live on the flesh of )<.<r 

 animals. The lion and the tiger prey upon the deer and the ante- 

 lope ; but if we go one step further we still arrive at the vegetable 

 kingdom as the source of animal nutrition. The deer and the ante- 

 lope are herbivorous creatures, and the flesh of their body is formed 

 directly from the plants they eat. So with the animals eaten by 

 man ; they are all grain or herb-eating animals, and supply to man 

 the materials they have obtained from the vegetable kingdom. At 

 the same time the best standard we can take of food is milk, which 

 is derived from the animal When human milk is examined, it gives 

 the following results in every 1000 parts : 



Water 870 



Butter 62 



Sugar . 63 



OiMI M 



Salts 5 



1000 



These five constituents of milk may be regarded as typical of .ill 

 kinds of food, whether obtained from the animal or vegetable kingdom. 

 Hence, we may class alimentary substances according as they are 

 represented by one or other of these constituents of milk. 



1. Aqueout. Water is required not only as the medium of coin, y- 

 ing the other substances into the body, but it forms a prominent 

 constituent of the body itself. Blood contains 790 parts of water to 

 210 parts of solid matter in every 1000. Muscles contain 770 parts of 

 water to 230 parts of solid ingredients. The brain and nerves contain 

 about 800 parts of water in 1000. If food does not contain water 

 naturally, it is taken into the system in the form of tea, coffee, beer, 

 and also in its pure state. The quantity of water taken with the food 

 should be about in the proportion of four to one, as we find it in milk. 

 We cannot however judge of the quantity contained in solid food till 

 we know its composition. Thus many substances which appear solid 

 contain large quantities of water. In potatoes, for instance, there are 

 75 parts of water in every 100. 



2. Olcaginout. The butter of the milk represents oily and fatty 

 matters in general, which seem to enter into the composition of all 

 healthy food. They are taken by the inhabitants of tropical coun- 

 tries in the seed of the cocoa-nut, as well as by those of the polar 

 regions from the fat of the seal and many kinds of fish. They are 

 obtained from both the animal and vegetable kingdoms, being kn..wn 

 by the name of suets, fats, and lards, from the former source ; and 

 oils and butter from the latter. 



3. Saccharine. The sugar of the milk represents Severn 1 substances 

 obtained from plants and used as food. Sugar itself varies in it* 

 composition according to its sources ; hence we have cane-sugar, 

 grape-sugar, maple-sugar, &c. Sugar has also a composition nearly 

 approaching that of starch, and this substance is very generally found 

 in the vegetable diet of man ; pure in the form of arrow-root, tapioca, 

 and sago ; combined in the flour of wheat and other cereal grasses. 

 Of all the animal products used as food, sugar is found alone in 

 milk. 



4. Proteinaceom. The casein of the milk, which, when *cp:u ;>*.. 1, 

 is known by the name of cheese, has, in common with two other 

 vegetable and animal substances, cjillcil tilu-ine and albumen, a prin- 

 ciple for their basis named protein. [PROTEIN.] These substances 

 form the chief part of the fabric of the body, anil in their capacity of 

 food perform a very different function in the body to the butter and 

 sugar before mentioned. 



5. Inorganic. The salts of milk are the saline substances which, 

 entering into the composition of various parts of the human body, are 

 necessary to its integrity and health. The importance of the presence 

 of these substances is frequently overlooked in food, and many diseases 

 of the human frame arise from their absence. They are conveyed 

 into the system in both animal and vegetable food ; but in common 

 salt we have an instance of a substance belonging to this class taken 

 directly from the mineral kingdom as food without the intervention 

 of an organic body. 



In addition to these forms of dietetic substances found in milk, i) 

 food of the adult human being constantly contains certain principles 

 which do not appear to be represented in the milk. Thus, the sub- 

 stances called condiment*, as the various spices, contain volatile oils, 

 which, although not essential to the diet of man, seem to exert a very 

 beneficial influence when taken into the system. In tea and coffee 

 there is a principle called theine, which seems to be the active ingre- 

 dient of these substances. In the fruit of plants also, we have acids, 

 as the citric, tartaric, malic, and oxalic acids, which seem to act very 

 beneficially in certain states of the system. As these substances seem 

 to act medicinally rather than dietetically, they may be properly 

 called, as a class, the medicinal constituents of food. The following 

 classification will give an idea of the kinds of food : 



