32 - The Cell 



Fig. 2-17. A modern micromanipulator with accessory equipment. This apparatus permits the operator to in- 

 ject fluid reagents into the cytoplasm, or into the nucleus of a cell, and to dissect the cell in various ways. Two 

 of the control levers that guide the microinstruments are shown (lower left). A photomicrographs camera is 

 mounted above the microscope. Above this (not shown in the photo) there is a television screen. This enables 

 the operator to observe the cells while they are being dissected and photographed. (Courtesy of M. J. Kopac, 

 New York University.) 



This experiment shows that the plasma mem- branes of the cell, directly from electron- 



brane is an integral part of the living proto- micrographic studies, and indirectly from 



plasm without which the cell cannot remain studies on the special properties of such 



alive. membranes. The plasma membrane (Fig. 



Much is now being learned about the struc- 2-13) proves to be about 8.0 millimicrons 



ture of the plasma and other intrinsic mem- thick in the desiccated state, although prob- 



