Day of a Scientist 167 



soluble nucleoproteins in which the nerve cells were known 

 to be particularly rich. 



Bill had been following very closely the work on changes 

 in nucleoprotein synthesis which occur after virus infection. 

 By tagging the relevant compounds with radioactive iso- 

 topes, it had been possible to show that in some cases 

 infection of a cell was followed within minutes, possibly 

 within seconds, by a cessation of normal synthesis and the 

 initiation of virus formation. This phenomenon approached 

 the time dimensions which people were beginning to de- 

 scribe for the setting up of permanent memory traces, and 

 it looked as though the methods used by the virus boys 

 could be adapted to the memory problem. 



Some preliminary experiments with photographic emul- 

 sions had been promising, and today they were going to do 

 an experiment with the microscopic bubble chamber they 

 had devised with the help of the physics department. The 

 physics boys had laughed and laughed when they first took 

 the problem to them: "It would be hard to maintain the 

 critical temperatures, pressures, and humidity on the appro- 

 priate scale. At the concentration of isotope you're using 

 you'd get all gummed up with secondary radiations, and 

 finally and above all, the bubbles in an ordinary chamber 

 are much too large to give you the resolution you need. The 

 whole point of a bubble chamber is to see things on a 

 macroscopic scale rather than having to resort to micro- 

 scopic analyses of photographs." 



One guy with a beard finally had volunteered to help 

 them, and one by one the problems had been pretty well 

 licked — the bubble size difficulty by the simple expedient 

 of adding a tiny bit of household detergent to the mix, 

 nobody knew quite why. 



Today they planned to look at eight slides with their 



