244 Discussion 



possible that the development of the pharyngeal glands and the fat 

 body also come under endocrine influence but, as far as I know, this 

 has not yet been examined closely in the honey-bee. 



Rockstein: Dr. Maurizio did imply in her paper that it was a 

 matter of endocrine control. I personally think that, generally, the 

 ultimate controlling influence will be found to lie in the endocrine 

 system. I do not think that Dr. Maurizio said that vitamins or 

 proteins were involved in this physiological senescence. She did 

 indicate that there was a depressed development of the pharyngeal 

 gland, which suggests hormone control. 



Comfort: Is the rate of loss of nerve cells different in summer and 

 winter bees? 



Rockstein: At the two levels of the brain which were counted there 

 were about 500 cells in the young bees and only about 325 in the old 

 bees, regardless of whether these were indoor (summer) bees without 

 a queen, or outdoor (summer) bees which had been living a normal 

 life in the hive. 



Comfort: In other words the difference in lifespan does not depend 

 on the difference in the rate of loss of cells? 



Rockstein: Yes, it does, because the old bees in both conditions 

 showed precisely the same degree of loss. The outdoor bees I had 

 were only seven weeks old, whereas, indoors, I had bees still living 

 at ten weeks of age. For one thing, my bees were exposed to light 

 24 hours a day. According to Dr. Maurizio the activity may have 

 nothing to do with age, but nevertheless I could not keep them alive 

 any longer under these conditions even on a completely unlimited 

 diet. I do think that the similarity in development of the overwinter- 

 ing or the summer-broodless bees is very significant. It points to an 

 entirely different phenomenon from that in the caged bees — namely 

 that these summer, "queenright" animals normally are not able to 

 attain their potential longevity owing to the demands of brood- 

 rearing upon their nutrition. As soon as you eliminate this really 

 exorbitant nutritional dernand, by removing the queen, the bees are 

 able to attain a lifespan of something like six to eight months. As 

 Prof. Wigglesworth suggested and Dr. Maurizio implied, the diet 

 does this, but where it produces its primary effect is not known. 

 Most probably it is through the endocrine system ; certainly, that is 

 evident in the effect upon the development of the pharyngeal glands 

 and of the fat body, which must be controlled at a biochemical level. 

 The most plausible explanation at a biochemical level is that of 

 altering hormone control. 



Nigrelli: What would happen if you did not feed the caged bees? 



Maurizio: They would be dead of starvation in two or three days. 



