-5= i After the injection or the introduction of the isotope into the biological. matter. It ie obvious that a good deal of that earlier work nill have to be done over, but it was satisfactory at the time since it did show a trend. information quickly during the war. This was a necessary device to get It cut down the number of animals that were used tc give a particular point, saving both time and materials. Somebody will have to do the hard routine unexciting work of going over a great deal of that earlier data and doing it on a large enough scale to fix more of these poir than we are able to fix now. concentration, In some cases it is not important to completely establish In fact, it is unrealistic to try tod so because the concentrations do not mean mich of themselves, it is only their relationship to other concentrations in tl biological material, (The body, for instance) that is important. When dealing with your Geiger counter equinment it will be pointed out therea a lot of errers, thelt is difficulty with the gecnetry of the set-up, their are difficu with the asning techniques. Tnere ere lots of loazes. All of those defects you want t take in your astride, but become feriliar with the techniquce--its purposes and the princ that govern it in general. I would like to have you leave this course withe the feeling that there is a ] to te learned yet, and there certainly is. You may get the impression in these three weeks that everything is known, and that is distinctly not the case. that has hardly been touched, or hardly been explored. We are at a front Cur equipment is greatly improv over what we had before the war, but it still leaves a lot. to be desired. Any of you who have an inventive frane ofmind should certainly give yourselves the opportunity of inventing improvements. They are badly needed. The equipment is too expensive for wic spread use, and medical schools and biology departments that use this equipment ordina: are not budgeted to operate on this level. the market is not saturated yet. Personnel is very expensive too, partly be: I can't promise you all better jobs than you have no: but I am quite sure you will be mich more efficient, efter you have had this training