2O6 CHARLES W. HARGITT. 



FAT STORAGE IN ANIMAL ECONOMY. 



The phenomenon of storage of fat among animals is a fact 

 very well, and long known, and its physiological significance 

 has been also generally recognized. Its occurrence in animals 

 which pass long periods of hibernation, during which no food is 

 taken, hence are dependent upon those reserve sources for sus- 

 tenance, is a matter equally well known and common in many 

 groups of animals. Among these are mammals, reptiles, amphibia 

 and fishes. In the last group are cases in which such reserves 

 are accumulated to meet extra and unusual demands which are 

 involved in extended migrations to distant spawning grounds. 

 And further dependence upon this store of energy is required 

 for the maturation and fertilization processes involved in the 

 reproductive crises common to many of this class of animals. 

 This phenomenon is known in numerous species among which 

 the salmon is a familiar example, with the rather tragic conse- 

 quence that this climactic performance is usually followed by 

 immediate or early death of the organisms. 



Some recent investigations and experiments of rather striking 

 importance have been made by Prof. C. W. Greene concerning 

 the physiological processes, both of the storage of this reserve 

 material and its later resorption by the tissues. (Bull. U. S. 

 Bureau of Fisheries, 1914, pp. 73-138.) Professor Greene has 

 studied this especially in the King salmon during the long fast 

 of the spawning migration. He shows how the 'storage takes 

 place in the musculature and connective tissues during the late 

 growth, and especially the voracious feeding just prior to the 

 migratory ordeal which involves hundreds of miles up great 

 rivers and against many and serious obstructions. The energy 

 consumed during this ordeal must be supplied by these reserve 

 sources of nutrition. And as just pointed out, the additional 

 demand involved the growth and ripening of the sexual products 

 and actual spawning of these at the end. It will be at once per- 

 ceived that for such an ordeal very large resources of energy 

 must be available and these are to be found almost wholly in 

 these reserve fat materials. Many other such experiments have 

 been made upon various species of animals such as amphibia, 

 reptiles, etc., all going to sustain the above cited findings; 



