17 



IS 



19 



20 



21 



oo 



PI. Ill — all figures concern Pelargonium stem 



Fig. 16: Cross section through normal tissue by CMR histological technique, XIO 

 Fig. 17: Cross section through injury in tumoral tissue 10 daA's after infection with Agrobac- 

 faciens, XIO 



Fig. IS: Injury in tumoral tissue three weeks after infection, XIO 



Fig. 19 and 23: Phenomenonofsolarization by X-rays. Compare the two cross sections through 

 stem. Fig. 19 shows the test microradiograph with white opaque crystals while ground is black 

 outside of section. On Fig. 23 the phenomenon of solarization is shown after longer exposure 

 time than for Fig. 19: an inversion shows black crystals and white ground outside of section, 

 XIO 



Fig. 20: This figure and the two following show a comparison of results obtained with different 

 voltages on bark tissue and film; here 10 kV — 20 niA — 5 min. — Lippmann film. The figure out- 

 lines the best result compatible with a necessary short exposure time. X16o 

 Fig. 21: 10 kV — ^20 m A — 1 min. — Kodalith film. With an identical voltage a coarser grained 

 though more sensitive film is poor in comparison with the fine grained film in Fig. 20. X165 

 Fig. 22: 4 kV — 25 niA — 4 min. — Kodalith film. Improvement of image is evident relative to 

 fig. 21 ; it is due to increasing contrast determined by decreasing voltage. X 165 



642 



