PHASE MICROSCOPY 



Fig. 4. Same field as Figure 3. Polaroids crossed. 3 



of transparent resin which had been placed 

 in the Izod test vise and hit with the test 

 hammer only hard enough to deform the 

 specimen slightly without breaking it. Ob- 

 serve (1) the incipient tears at the notch 

 corners and (2) the two sets of fracture 

 cracks on the left. Figure 4 shows the same 

 field between crossed Polaroids. The intense 

 strain pattern, due to plastoelastic deforma- 

 tion, is divided into two sections, each of 

 which converges on one of the incipient tears 

 at the notch corners. The fracture cracks 

 extend into the strain patterns but distort 

 them only very slightly. In the full 3^^^-inch 

 thickness of the specimen, these features 

 were not readily resolvable but the adjoining 

 strain patterns of lower order due to elastic 



deformutiun, which were obliterated in grind- 

 ing to the .25-mm thickness, were fairly 

 leadily resolvable. At half-thickness of the 

 specimen, the latter patterns were quite clear 

 and the former was just beginning to 

 emerge. 



REFERENCES 



1. Rogers, A. F. and Kerr, P. F., "Optical Min- 



eralogy," McGraw-Hill, New York, 1942. 



2. Chamot, E. M., and Mason, C. W., "Handbook 



of Chemical Microscopy," Chapter 5, John 

 Wiley & Sons, New York, 1958. 

 Kennedy, G. C, "The Preparation of Polished 

 Thin Sections ," £;con. (?eoL , 40, 353-59 (1945) . 



4. Insley, H. and Frechette, V. D., "Micros- 

 copy of Ceramics and Cements." Academic 

 Press, New York, 1955. 



5. RocHOw, T. G., "Microscopy in the Resin In- 

 dustry," Ind. Eng. Chem. Anal. Ed., 11, 629- 

 34 (1939). 



6. RocHOW, T. G. and Gilbert, R. L., Chapter 

 on "Resinography" in Volume V of Matiello's 

 "Protective and Decorative Coatings," John 

 Wiley & Sons, New York, 1946. 



7. Weatherhead, a. V., "A New Method for the 

 Preparation of Thin Sections," Mineralog. 

 Mag., 25, 529-33 (1940). 



8. Norton, F. H., "Refractories," McGraw-Hill, 

 New York, 1946. 



9. Wright, R. E. and Wolff, H. I., "Refractory 

 Problems in the Production of Hydrogen by 

 Pyrolysis of Natural Gas," /. Am. Ceram. 

 Soc. ,31, 31-38 (1948). 



R. E. Wright 



Phase microscopy (See also pp. 365, 452) 



ANOPTRAL MICROSCOPE* 



In 1944 the author began searching for 

 possible means of detecting more clearly in 

 the microscope the structure of living cells 

 and tissues. Most excellent microscopes 

 have been in use for nearly a hundred years, 



* Exerpt from paper in Mikroskopie, 9, 1954, 

 Nos. 1-4, pp. 80. 



and they reproduce very well the structure 

 of objects which are fixed and stained and 

 usually embedded in Canada balsam. How- 

 ever, there are certainly many unknown 

 fundamental facts that can only be revealed 

 by studying the living preparation directly. 

 Life is sometimes characterized much better 

 by motion, growth, propagation and ex- 

 change of the cellular constituents than it is 



476 



