Summary and General Discussion 371 



group of planaria is fed shredded, naive worms. On subsequent 

 training, the group which ate trained worms was found to acquire 

 that conchtioned response significantly more rapidly than the 

 group which ate naive worms. This experiment was run blind 

 in our laboratory, and the results confirmed previous reports by 

 McConnell's group. One is probably justified in assuming the 

 absence of enzymes in the planarian gut, which would degrade 

 macromolecules. The reason I refer to this work is to ask what 

 sort of mechanism you would suggest to account for these results. 



Gerard: WeU, it is even more unbelievable than the earlier 

 stuff, but I still tliink that what I was saying was relevant to your 

 question. I would have to assume that these informed molecules 

 are not completely degraded in being digested and absorbed, and 

 so supply templates on which the organized learning can be based, 

 just as for the tail regrowing a head with its neurons. 



I wonder if we should not let some of tlie other people get in 

 before pushing this one point. 



Morrell: I had hoped to get a specific comment on the plausi- 

 bility of my suggestion for chemical "protection." I wonder 

 whether a possible mechanism for preservation of an imposed 

 shift in charge distribution might be the bonding of the charged 

 moiety to phospholipid. Conceivably such bonding might not 

 only protect this given molecular rearrangement, but also fix it 

 to sites within the membrane where influences on synaptic trans- 

 mission might be expected. There is some evidence by Tobias 

 which indicates that axons treated with proteases continue to 

 conduct action potentials for many hours, while treatment with 

 lipase rapidly abolishes conduction. Tobias (personal communi- 

 cation) has now found that similar treatment with ribonuclease 

 also impairs the capacity of the axon to generate action potentials. 

 Moreover, there is some preliminary evidence from Dr. Herzenberg 

 (personal communication) to the effect that the DNA-RNA speci- 

 fication system may not only regulate protein synthesis but also 

 influence molecules containing phospholipid. In fact, these lipid 

 molecules are antigenic and thus conceivably could provide a 

 chemical mechanism for cell recognition. 



Gerard: I think that is fine to have on the record. I had rather 

 not push it, although I must say that I heard recently that Tobias' 



