248 Morris Rockstein 



weeks was obtained for approximately 4,000 of the same strain 

 of honey-bee maintained indoors, in a more recent study 

 involving changes in alkaline and acid phosphatase in ageing 

 bees (Rockstein, 1953). For a similar study of 2,700 "queen- 

 right" bees, marked with coloured lacquer immediately after 

 emergence and returned to the hive to engage in normal hive 

 activities (during the summer months), the last sample of 

 bees had to be taken at 51 days of age. These values compare 

 well with observations of apiculturists and other students of 

 the biology of the honey-bee (see Rockstein, 1950fc). Indeed, 

 Dr. Maurizio's own studies (1954) include data for two strains 

 of Italian bees of maximum lifespans of 54 and 62 days, 

 respectively, maintained in the hive during summer months. 



In the earlier studies (Rockstein, 1950a), the number of 

 neurones at two distinct levels of the honey-bee brain was em- 

 ployed as an anatomical criterion for biological old age; the 

 absolute number of cells remaining in the brains of old bees 

 (as well as the percentage loss from emergence to old age) 

 was remarkably similar (325 ; 350) for both kinds of old bees, 

 whether they were living the normal lives of the hive bee or 

 were maintained indoors in a small queenless colony under the 

 conditions described. This loss of about 35 per cent of the 

 original number of brain cells in the adult worker bee is 

 singularly similar to that of a 35 to 40 per cent loss in mam- 

 malian brain cell number reported for humans by Hodge 

 (1894), Ellis (1919, 1920), Andrew (1938) and Gardner (1940) 

 and for the white rat by Hatai (1902) and by Inukai (1928). 



From a recent study of the decline with age in the activity 

 of enzymes concerned with the energizing of flight activity in 

 the common housefly, from emergence to senility, longevity 

 data have been obtained for thousands of male and female 

 flies of the NAIDM standard laboratory strain of houseflies, 

 which had been intensively inbred for more than one hundred 

 generations. In our laboratory these animals are reared and 

 maintained on a standardized laboratory diet in an air- 

 conditioned room kept at 80° f and 45 per cent relative 



