808 ADVENTURES IN RADIOISOTOPE RESEARCH 



content of barium carbonate amounts to 6.1 per cent only. A burning of a fat 

 sample and the conversion of the carbon obtained into barium carbonate leads 

 thus to a product the activity of which makes out 9.1 per cent only of the activity 

 of fat of the same weight, this figure being increased to 1 1 when taking into account 

 the reflecting power of barium for the j5-rays emitted by the sample. 



RESULTS 



Some of the results obtained when comparing the i*C content of 

 irradiated mice and that of controls is seen in the following tables. 



Table 1. — Percentage Inhibition by an X-ray 



Dose of 880 r of the Incorporation of ^^C into 



Purines of Desoxybibonucleic Acid Prepared 



FROM THE Liver of Suckling Rats 



Table 2. — Percentage Carbon Content 



Ascertained in Some of our Tissue 



Samples 



Liver fat 65.2 



Liver protein 48.8 



Intestinal mucosa fat 64.0 



Intestinal mucosa protein 47.3 



20 mice weighing 21 — 27 gm were irradiated. Half of these — having 

 an average weight of 23.5 gm each — were injected immediately, half 

 after the lapse of 6 hr with 0.15 ml labelled acetate having an activity 

 of 49,200 counts per min. A third group of 10 mice — aggregate weight 

 238 gm — was injected without being irradiated. All mice were killed 

 1.5 hours after the injection. 



We arrived at the figure 49,200 stated above by dissolving a known 

 aliquot of the injected acetate in 50 mgm of a concentrated sodium acetate 

 solution having the same vapour pressure as the atmosphere at the time 

 of measurement and measuring the activity of the solution. All activity 

 data of the tables 3—6, which contain some of the results obtained, are 

 such of a 50 mg u sample. We did not correct for the different reflecting 

 power of the acetate solution, fat samples and so on. The correction to 

 be employed is very restricted. Furthermore, we were interested primarily 



