FLYING SPOT MICKOSCOPY 



JUUl 



COMPOSITE IN 

 SPECIMEN PLANE 



h,"^ 



I?' 



•^I»l.l, I 



Fig. 5. Composite ultraviolet visible light system. 



of the same intensity as the spot. The video obtained uUraviolet absorption image of the 



system could then be adjusted to the proper remainder of the cell. 



level to view the entire field and the danger 



of ultraviolet damage to the control area 



was removed. This arrangement is shown in 



Figure 5. 



By reversing the pulse polarities, the con- 

 verse situation may be achieved. The back- 

 ground is in ultraviolet and a portion of the 

 cell is protected and simultaneously viewed 

 in visible light. 



Time-lapse motion pictures demonstrating 

 the application of the above briefly described 

 techniques to living cell systems have been 

 taken to demonstrate the following experi- 

 ments : 



(1) Contmuous, or intermittent, intense 

 differential ultraviolet irradiation of the 

 nucleolus of a Hvmg cell with simultaneously 

 obtained ultraviolet absorption images of the 

 remainder of the cell (Figure 6). 



(2) Continuous, or intermittent, intense 

 ultraviolet irradiation of the nucleolus of a 

 living cell with a simultaneously obtained 

 visible Ught image of the remainder of the 

 cell. 



(3) Continuous, or intermittent, intense 

 differential ultraviolet irradiation of the 

 nucleus of a living cell with a simultaneously 



Fig. 6. Ultraviolet absorption image of a living 

 HeLa cell. The brightened spot centered in the 

 nucleolus represents a one micron square micro- 

 beam of ultraviolet irradiation. 



337 



