117 



MAZIA: Is there a possibility that preliminary washing in physiologi- 

 cal salt solution is enough to remove the divalent ions by straightforward ion 

 exchange? 



SPIEGELMAN: One experiment would be extremely interesting here. 

 That is to take purified transforming principle, put it through your procedure, 

 and bring it back agam to its precipitated form and then see if it is still active. 



it. 



CHARGAFF: The transforming principle does not have the protein in 



POLLARD: 



cleoprotein? 



Suppose you did not purify it and you used it just as nu- 



CHARGAFF: With very few exceptions, you cannot get nucleoproteins 

 from bacteria. There is only one described in the literature. You cannot get 

 a real nucleoprotein from pneumococcus. At least no one has been able to do 

 so. No one has isolated nucleoprotein. 



MAZIA: Has anyone tried working deliberately at low ionic strength? 



CHARGAFF: I think so but cannot be sure. We have tried other mate- 

 rials, not thinking of the transforming principles, to prepare nucleoprotein and 

 so far, have only succeeded in the case of tubercle bacilli. 



KAPLAN: It is interesting the calcium apparently has an important 

 effect on mutual adhesiveness of cells. Coman showed some time back, that 

 tumor cells can be separated from one another with relative ease and that their 

 intercellular matrix contains a decreased amount of calcium. If you treat nor- 

 mal tissues with agents that deplete calcium, you can show a similar decrease 

 in adhesiveness of cells and an increased capacity of the cells to wander away 

 from one another. 



