AUTORADIOGRAPHY 



347 



B 



I- 



C- 



Fig. 7-13. P^- aiiti)ni(lioj;r.un of Ijarley roots. .-1, when P-*- Wits api^lied several 

 centimeters back of root tip, there was considerable translocation; B, note selective 

 accumulation at root tip; (', when same amount of P^^ was applied at root tip, less 

 activity was transported to other parts of phtnt than when application was made at 

 position A. {Courtesy of H . Wiehe.) 



Fig. 7-14. Measurement of bone growth by Ca^'" autoradiograms. A represents low 

 concentration of radioactivity in bone formed between time of Ca''^ dosage and 

 sacrifice, (a) Distal end of femur of pig A grew 2.1 mm in 10 days, {h) In a com- 

 parative study, the corresponding growth of bone of pig B, on a low dietary intake, was 

 7.9 mm in 45 days, whereas (c) the growth for pig C, on a high dietary intake, was 

 10.0 mm in 45 days. 



other similar studies that, once Ca^^ is deposited in bone, it tends to stay 

 in its original location and that new bone formed has a much lower con- 

 centration of radioactivity (note region A). Thus it becomes easy to 

 visualize the growth that has occurred between the time of administra- 

 tion of the radioactivity and the sacrifice of the animal. Quantitative 



