Proceedings of the British Association. 56S 



from what constituents of vegetables the blood of the graminivorous 

 animals is produced. The nitrogenized compounds of vegetables form- 

 ing the food of graminivorous animals are called vegetable fibrine, vege- 

 table albumen, and vegetable caseine. Now, analysis has led to the 

 interesting result, that they are exactly of the same composition in 100 

 parts; and, what is still more extraordinary, they are absolutely identi- 

 cal with the chief constituents of the blood — animal fibrine and animal 

 albumen. By identity, be it remarked, we do not imply similarity, but 

 absolute identity, even as far as their inorganic constituents are con- 

 cerned. These considerations shewed the beautiful simplicity of nutri- 

 tion. In point of fact, vegetables produce, in their inorganism, the 

 blood of all animals. Animal and vegetable life are therefore most 

 closely connected. The Professor has still to account for the use of the 

 substances in food which are absolutely destitute of nitrogen ; but which 

 we know are absolutely necessary to animal life. In all these we find a 

 great excess of carbon, and but very little oxygen. By a train of admi- 

 rable reasoning, the Professor arrives at the interesting conclusion, that 

 they are solely exhausted in the production of animal heat, being convert- 

 ed by the oxygen of the air into carbonic acid and water. This portion 

 of the report contained an ingenious and important view of the use of 

 bile in the animal economy, the truth of which quantitative physiology 

 dare not deny. When exercise is denied to graminivorous and omnivor- 

 ous animals, this is tantamount to a deficient supply of oxygen. The 

 carbon of the food not meeting with sufficient oxygen to consume it, it 

 passes into the compounds containing a large excess of carbon and 

 deficiency of oxygen ; or, in other words, fat is produced. Liebig 

 concludes, that fat is altogether an abnormal and unnatural production, 

 arising from the adaptation of nature to circumstances, and not of 

 circumstances to nature — altogether arising from a disproportion of 

 carbon in the food to that of oxygen respired by the lungs, or absorbed 

 by the skin. Wild animals in a state of nature do not contain fat. The 

 Bedouin, or Arab of the Desert, who shews with pride his lean, muscu- 

 lar, sinewy limbs, is altogether free from fat. And the Professor points 

 out the diseases arising from this cause. From all that has transpired, 

 we may sum up the nutritious elements of food as follows. The ingre- 

 dients adapted for the formation of the blood, and which the Professor 

 calls the plastic elements of nutrition, are as follows : — Vegetable 

 fibrine, vegetable albumen, vegetable caseine, animal flesh, animal 

 blood. The other ingredients of food being fitted to retain the tempe- 

 rature of the body, he calls the elements of respiration. They are— fat, 

 starch, gum, cane sugar, grape sugar, sugar of milk, pectine, bassorine, 



