62 INANITION AND MALNUTRITION 



twelve completely sterilized generations on a nutrient solution containing baker's 

 yeast and citric acid. In many experiments on other media (e.g. filter paper 

 plus cane sugar and salts; likewise with addition of casein, edestin, egg albumin, 

 milk or a mixture of aminoacids), the larvae attained normal size, but did not 

 undergo metamorphosis. Sterile flies, grown on sterile bananas or potatoes, show 

 no sexual development. Yeast is apparently the only adequate food for these 

 flies. Loeb and Northrop ('17) and Northrop ('17) found that, unless yeast is 

 added, growth of Drosophila ceases on aseptic cultures and that by inadequate 

 feeding during the larval period the total normal duration of life of nineteen 

 days may be prolonged up to twenty-nine days. The length of life of the imago 

 is not affected by the earlier period of malnutrition. 



Baumberger ('19) concluded that "Drosophila living in fermenting fruit 

 are dependent for their food supply on the synthetic and absorptive powers of 

 yeast cells. In a similar manner, my study of the relation of Musca domestica 

 to manure, of Desmometopa to decaying meat, and of Sciara and Tyroglyphus 

 to decaying wood shows clearly that these Arthropods also feed on microorgan- 

 isms." Both adults and larvae of Drosophila require sugar as food, but cannot 

 live on sugars or nucleoproteins alone. Since Drosophila can be reared normally 

 on yeast nucleoprotein, sugar and salts, any "special substance" required must 

 be present in this mixture. The larvae can be maintained for a long time on a 

 minimum of protein (banana diet) at constant or slowly increasing size, and may 

 later develop to normal size on adequate (yeast) diet. The total span of life 

 may therefore be increased eleven days to forty days of more. There is a 

 tendency for the larva to pupate after a certain length of time, whether it reaches 

 the maximum size before this period or is still undersized from malnutrition. 



Pearl and Parker ('24) made an extensive experimental study of the duration 

 of life in Drosophilia melanogaster during complete (total) inanition. The 

 mean duration is slightly less than two days. The duration in the females is 

 more variable than in the males, both absolutely and relatively, but in both 

 sexes the variability is relatively much less than during full feeding. The females 

 are longer lived than the males, during inanition as well as when full fed. 

 Although the normal wild-type flies during full feeding live about three times 

 as long as the vestigial type, during total inanition the mean duration of life is 

 nearly the same in both types. The genetic significance of these results is 

 discussed. 



Vinokuroff ('22) found the mean duration of life in the common housefly 

 {Musca domestica) to be 1.3 days when starved without water, or 1.8 days on 

 water alone. Similar observations were made by Glaser ('23). 



Lepidoptera. — Lucas (1826) noted death from starvation in the moth Bombyx 

 in three days; in another case (Bombyx cerura Schrank) in 15 days, in June. In 

 the saturniid moths, which normally take no food in the imaginal stage and live 

 only about eight days at ordinary temperature, Rau and Rau ('12) found the 

 duration of life extended to about 18 days at low temperatures. 



Semper ('81) stated that T. Gentry of Philadelphia, found underfed larvae of 

 Acronyeta (sp.?) produce smaller pupae and moths. Von Linden ('07) observed 

 that one specimen of adult Hylophila prasinana lost 43 percent of its body weight 



