ANIMAL CHEMISTRY. 



sions deduced from them as the origin of 

 animal heat, are destitute of practical value 

 in regard to this question, since we have 

 seen that the quantity of oxygen consumed 

 varies according to the temperature and 

 density of the air, according to the degree 

 of motion, labour, or exercise, to the amount 

 and quality of food, to the comparative 

 warmth of the clothing, and also according 

 to the time within which the food is taken. 

 Prisoners in the Bridewell at Marienschloss 

 (a prison where labour is enforced,) do not 

 consume more than 10'5 oz. of carbon daily ; 

 those in the House of Arrest at Giessen, 

 who are deprived of all exercise, consume 

 only 8*5 oz. ; (6) and in a family well known 

 to me, consisting of nine individuals, five 

 adults, and four children of different ages, 

 the average daily consumption of carbon for 

 each, is not more than 9 - > oz. of carbon.* 

 We may safely assume, as an approxima- 

 tion, that the quantities of oxygen consumed 

 in these diflerent cases are in the ratio of 

 these numbers j but where the food contains 

 meat, fat, and wine, the proportions are 

 altered by reason of the hydrogen in these 

 kinds of food which is oxidised, and which, 

 in being converted into water, evolves much 

 more heat for equal weights. 



The attempts to ascertain the amount of 

 heat evolved in an animal for a given con- 

 sumption of oxygen have been equally 

 unsatisfactory. Animals have been allowed 

 to respire in close chambers surrounded 

 with cold water; the increase of tempera- 

 ture in the water has been measured by the 

 thermometer, and the quantity of oxygen 

 consumed has been calculated from the 

 analysis of the air before and after the ex- 

 periment. In experiments thus conducted, 

 it has been found that the animal lost about 

 fa more heat than corresponded to the 

 oxygen consumed; and had the windpipe 

 of the animal been tied, the strange result 

 would have been obtained of a rise in the 

 temperature of the water without any con- 

 sumption of oxygen. The animal was at the 

 temperature of 98 or 99, and the water, 

 in the experiments of Despretz, was at 

 47'5. Such experiments consequently 

 prove, that when a great difference exists 

 between the temperature of the animal body 

 and that of the surrounding medium, and 

 when no motion is allowed, more heat is 

 given off than corresponds to the oxygen 

 consumed, In equal times, with free and 

 unimpeded motion, a much larger quantity 

 of oxygen would be consumed without a 

 perceptible increase ir .he amount of heat 

 lost. The cause of these phenomena is 



* In this family, the monthly consumption was 

 151 Ihs. of brown bread, 70 Ibs. white bread, 132 

 Ibs. meat, 19 Ibs. sugar, 15'9 Ibs. butter, 57 maass 

 (about 24 gallons) ot milk ; the carbon of the po- 

 tatoes and other vegetables, of the poultry, game, 

 and wine consumed, having been reckoned as 

 equal to that contained in "the excrementitious 

 matters, the carbon of the above articles wascon- 

 siderf d as Seing converted into carbonic acid. 



obvious. They appear naturally both m 

 man and animals at certain seasons of the 

 year, and we say in such cases that we are 

 freezing, or experience the sensation of cold. 

 It is plain, that if we were to clothe a man 

 in a metallic dress, and tie up his hands and 

 feet, the loss of heat, for the sume consump- 

 tion of oxygen, would be far greater than 

 if we were to wrap him up in fur and 

 woollen cloth. Nay, in the latter case, we 

 should see him begin to perspire, and warm 

 water would exude, in drops, through the 

 finest pores of his skin. 



If to these considerations we add, that de- 

 cisive experiments are on record, in which 

 animals were made to respire in an unna- 

 tural position, as for example, lying on the 

 back, with the limbs tied so as to preclude 

 motion, and that the temperature of their 

 bodies was found to sink in a degree appre- 

 ciable by the thermometer, we can hardly 

 be at a loss what value we ought to attach 

 to the conclusions drawn from such experi- 

 ments as those above described. 



These experiments and the conclusions 

 deduced from them, in short, are incapable 

 of furnishing the smallest support to the 

 opinion that there exists, in the animal body, 

 any other unknown source of heat, besides 

 the mutual chemical action between the ele- 

 ments of the food and the oxygen of the air. 

 The existence of the latter cannot be doubtpd 

 or denied, and it is amply sufficient to ex- 

 plain all the phenomena. 



VII. If we designate the production o( 

 force, the phenomena of motion in the ani- 

 mal body as nervous life, and the resistance, 

 the condition of static equilibrium, as vege- 

 tative life ; it is obvious that in all classes 

 of animals the latter, namely, vegetative life, 

 prevails over the former, nervous life, in the 

 earlier stages of existence. 



The passage or change of matter from a 

 state of motion to a state of rest appears in 

 an increase of the mass, and in the supply 

 of waste; while the motion itself, or the 

 production of force, appears in the shape of 

 waste of matter. 



In a young animal, the waste is less than 

 the increase; and the female retains, up to 

 a certain age, this peculiar condition of a 

 more intense vegetative life. This condition 

 does not cease in the female as in the male, 

 with the complete development of all the 

 organs of the body. 



The female in the lower animals, is, ai 

 certain seasons, capable of reproduction of 

 the species. The vegetative life in her or- 

 ganism is rendered more intense by certain 

 external conditions, such as temperature, 

 food,&c. ; the organism produces more than 

 is wasted, and the result is the capacity of 

 reproduction. 



In the human species, the female organism 

 is independent of those external causes 

 which increase the intensity of vegetative 

 life. When the organism is fully developed, 

 it is at all times capable of reproduction of 

 the pecies ; and infinite wisdom has given 



