LAMELLAR SYSTEMS 159 



( 1 ) The study of labile components such as photopiginents at relatively 

 low temperatures. As mentioned earlier, the possibility of making thin films 

 of photopigments such as extracted rhodopsin, and then examining them at 

 low temperatures with the electron microscope, appears to be quite promising. 



(2) The study of tissues with their water components (hydration shells 

 and extracellular water) retained in their native states. 



Many other applications can be foreseen in connection with x-ra\ diffrac- 

 tion studies, including investigations of the parameters connected with long- 

 term preservation of biological systems, and the possibility of exploring new 

 phenomena which might occur at these extremely low temperatures. 



