MEDICAL APPLICATIONS 219 



required. Viewing a picture made with an objective of high resolution 

 of the tissue superimposed on a picture of the tracks with a stereoscope 

 may be helpful. Another method is to combine two pictures, one at 

 the tissue and the other at the track level (Boyd, 1947; Herz, 1950). 



10. PHYSIOLOGICAL APPLICATIONS 



The increased visibility Avith phase microscopy makes possible many 

 experiments with living processes that were not possible with brightfield 

 methods. One of the most spectacular teaching demonstrations is the 

 cyclosis of the cells of the epithelium from the inner scales of an onion 

 bulb. With the 0.2A±0.25X diffraction plate one can see the plastids, 

 mitochondria, and other cell constituents pass in review. The use of 

 other materials like Elodca and Nitella are possible although the green 

 chlorophyll obscures the more transparent constituents. Amoeboid 

 movement is of interest because the ecto-endoplasm boundaries show 

 clearly. Protozoa or cells from the clam gill are suitable for ciliary 

 motion study. Changes from paralysis by sensitive serum have been 

 described for P. hursaria (Section 3.2). The effects of drugs and other 

 agents on motion may be followed under the phase microscope. 



Sol-gel reversals and concentration gradients may also be observed. 

 Starch hydrolysis and other digestive changes can be studied. The 

 changes in fibers between feed and feces may be seen. Chemical and 

 vitamin effects may be observed. Growth changes in microorganisms 

 can be followed in permanent records when phase motion picture films 

 are made. Microorganisms may be used in testing the potency of drugs 

 for pharmacology. Evaluation of radiation effects is aided by phase 

 microscopy (X-ray, Chase and Smith, 1949; ultraviolet, Kimball, 1949). 

 In fact, a broad field is opened by phase microscopy for the study of 

 function. 



11. MEDICAL APPLICATIONS 



No sharp distinction is possible between experimental biology and 

 medicine other than the aim of the in\'estigation. Much of what has 

 been written before, especially on microorganisms and histology, is of 

 equal interest to those in the field of medicine. Yet certain types of 

 microscopy are more apt to be selected with respect to disease. These 

 will now l)e considered. 



Much of the laboratory woi'k of clinical diagnosis can be lightened by 

 phase microscopy. Urine sediments and casts can be seen more clearly 

 with the phase microscope (Gradwohl, 1948; Magliozzi, 1948). Vaginal 

 smears can be examined without staining, as suggested by Albertini 

 (1948), by Culiner and Gluckman (19486), and by Kunge et al. (1949). 



