USES OP THE STARCH, SUGAR, &c. 



23 



the true mlrogenized constituents of the 

 food of graminivorous animals; all other 

 nitrogenized compounds, occurring in plants, 

 are either rejected by animals, as in the case 

 of the characteristic principles of poisonous 

 and medicinal plants, or else they occur in 

 the food in such very small proportion, that 

 they cannot possibly contribute to the in- 

 crease of mass in the animal body. 



The chemical analysis of these three sub- 

 stances has led to the very interesting result 

 that they contain the same organic elements, 

 united in the same proportion by weight ; 

 and, what is still more remarkable, that they 

 are identical in composition with the chief 

 constituents of blood, animal fibrine, and 

 albumen. They all three dissolve in con- 

 centrated muriatic acid with the same deep 

 purple colour, and even in their physical 

 characters, animal fibrine and albumen are 

 in no respect different from vegetable fibrine 

 and albumen. It is especially to be noticed, 

 that by the phrase, identity of composition 

 we do not here imply mere similarity, but 

 that even in regard to the presence and 

 relative amount of sulphur, phosphorus, and 

 phosphate of lime, no difference can be 

 observed. (8) 



How beautifully and admirably simple, 

 with the aid of these discoveries, appears the 

 process of nutrition in animals, the forma- 

 tion of their organs, in which vitality chiefly 

 resides ! Those vegetable principles, which 

 in animals are used to form blood, contain 

 Ahe chief constituents of blood, fibrine and 

 albumen, ready formed, as far as regards 

 their composition. All plants, besides, con- 

 tain a certain quantity of iron, which re- 

 appears in the colouring matter of the blood. 

 Vegetable fibrine and animal fibrine, veget- 

 able albumen and animal albumen, hardly 

 differ even in form ; if these principles be 

 wanting in the food, the nutrition of the 

 animal is arrested ; and when they are pre- 

 sent, the graminivorous animal obtains in 

 its food the very same principles on the pre- 

 sence of which the nutrition of the car- 

 nivora entirely depends. 



Vegetables produce in their organism the 

 blood of all animals, for the carnivora, in 

 consuming the blood and flesh of the grami- 

 nivora, consume, strictly speaking, only the 

 vegetable principles which have served for 

 the nutrition of the latter. Vegetable fibrine 

 and albumen take the same form in the 

 stomach of the graminivorous animal as 

 animal fibrine and albumen do in that of the 

 carnivorous animal. 



From what has been said, it follows that 

 the development of the animal organism and 

 its growth are dependent on the reception 

 of certain principles identical with the chief 

 constituents of blood. 



In this sense we may say that the animal 

 organism gives to blood only its form ; that 

 it is incapable of creating blood out of other 

 substances which do not already contain 

 the chief constituents of that fluid. We 

 cannot, indeed, maintain tha^ the anima 1 



! organism has no power to form other com- 

 pounds, for we know that it is capable of 

 producing an extensive series of compounds, 

 differing in composition from the chief con- 

 stituents of blood ; but these last, which form 

 the starting point of the series, it cannot 

 produce. 



The animal organism is a higher kind of 

 vegetable, the development of which begins 

 with those substances, with the production 

 of which the life of an ordinary vegetable 

 ends. As soon as the latter has borne seed, 

 it dies, or a period of its life comes to a ter- 

 mination. 



In that endless series of compounds, which 

 begins with carbonic acid, ammonia, and 

 water, the sources of the nutrition of veget- 

 ables, and includes the most complex consti 

 tuents of the animal brain, there is no blank, 

 no interruption. The first substance capable 

 of affording nutriment to animals is the last 

 product of the creative energy of vegetables. 



The substance of cellular tissue and of 

 membranes, of the brain and nerves, these 

 the vegetable cannot produce. 



The seemingly miraculous in the produc- 

 tive agency of vegetables disappears in a 

 great degree, when we reflect that the pro- 

 duction of the constituents of blood cannot 

 appear more surprising than the occurrence 

 of the fat of beef and mutton in cocoa beans, 

 of human fat in olive oil, of the principal 

 ingredient of butter in palm oil, and of horse 

 fat and train oil in certain only seeds. 



X. While the preceding considerations 

 leave little or no doubt as to the way in which 

 the increase of mass in an animal, that is, 

 its growth, is carried on, there is yet to be 

 resolved a most important question, namely, 

 that of the function performed in the animal 

 system by substances containing no nitrogen, 

 such as sugar, starch, gum, pectine, &c. 



The most extensive class of animals, the 

 graminivora, cannot live without these sub- 

 stances ; their food must contain a certain 

 amount of one or more of them, and if these 

 compounds are not supplied, death quickly 

 ensues. 



This important inquiry extends also to the 

 constituents of the food of carnivorous ani- 

 mals in the earliest periods of life ; for this 

 food also contains substances which are not 

 necessary for their support in the adult stale. 



The nutrition of the young of carnivora 

 is obviously accomplished by means similar 

 to those by which the graminivora are nou- 

 rished ; their development is dependant on 

 the supply of a fluid, which the body of the 

 mother secretes in the shape of milk. 



Milk contains only one nitrogenized con- 

 stituent, known under the name of caseine ; 

 besides this, its chief ingredients are butter, 

 (fat), and sugar of milk. 



The blood of the young animal, its mus- 

 cular fibre, cellular tissue, nervous matter, 

 and bones, must have derived their origin 

 from the nitrogenized constituent of milk, 

 the caseine ; for butler and sugar of milk 

 contain no nitrogen. 



