Rats of 23 and of 100 days of age were deprived of food for periods ranging from 0 to 192 hr. and then allowed access to pure milk or a quinine-milk solution for 24 hr. With increasing deprivation there was an increment in amount of both solutions consumed, except that 100 day rats on pure milk drank maximally at 48 hr. deprivation. When the relative ingestion of quinine-milk to milk at each deprivation level was plotted as a function of percentage of weight loss, the functions appeared to be the same for the 2 ages, "supporting the hypothesis that severity of food deprivation is proportional to the percentage of weight loss." From Psyc Abstracts 36:02:2EF20W. (PsycINFO Database Record (c) 2006 APA, all rights reserved)