METABOLISM 305 



pioneers in crossing the deserts of Nevada killed their 

 famished oxen for food they were disappointed to find 

 this marrow replaced by fluid; the animals had nearly 

 exhausted this reserve along with other deposits. Some 

 adipose tissue is usually found about the heart, behind 

 the eyes, and in the mesentery. 



In well-fattened individuals these accumulations are 

 supplemented by others. Chief of these is the sub- 

 cutaneous fat, a layer between the skin and the muscles. 

 This may be indefinitely increased and its prominence 

 determines our judgment as to whether a subject is 

 obese or not. Corpulent persons have much adipose 

 tissue in the great omentum, making this appendage 

 to the stomach a massive affair instead of the filmy apron 

 which it is ordinarily. We may assume that the average 

 human adult has at least 4 or 5 pounds of fat in his 

 system. 



The ultimate service of this fat is to be oxidized and to 

 contribute its energy to the working tissues, particularly 

 the skeletal muscles. To perform this function it must 

 first be carried from the seat of its temporary storage to 

 the contractile organs. This transfer occurs most 

 actively in periods of fasting when the organism is 

 feeding upon its own stores. The blood of a starving 

 animal may be richer in fat than is usual during mixed 

 feeding for it is engaged in this work of transportation. 



When fat is fully oxidized the only end-products are 

 carbon dioxid and water. In certain pathologic condi- 

 tions, notably in severe diabetes, the oxidation of fat is 

 incomplete and certain less simple compounds are formed. 

 These are of an acid character and their accumulation in 

 the blood and elsewhere may be responsible for a pro- 

 found poisoning. This is appropriately called an 

 acidosis. Very much as when we fail to burn coal cleanly 

 and completely we get the poisonous carbon monoxid, 

 so when fat is not effectually oxidized in the body we 

 have generated products which are immeasurably more 

 injurious than the normal ones. 



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