FREEZING-DRYING PREPARATION OF TISSUE 7 



soldered to Vie in. brass rods which are threaded into the aluminum 

 standard. An instrument panel is mounted under G to carry the 

 rheostats and meters for controlling the heating current for the 

 diffusion pumps and the paraffin chamber. 



Detail of 

 joints A and J 



Detail of 

 paraffin heater D 



Fig. 1, The Packer-Scott (1942) freezing-drying apparatus. 



Fig. 2. Arrangement for supporting the Packer-Scott (1942) 

 freezing-drying apparatus. 



In order to ascertain something of the state of dehydration of 

 the tissue the ionization pressure gauges F and I in Figure 1 are 

 fitted into tube G. When the rate of evaporation falls to a very 



