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Plate I 



The appearance of organelles in Paranicciuin under phase conlrasl and electron microscopy. (In A and B the 

 line represents 10 /' ; in C. D. and E it represents 1 //.) 



A. Food-intake system, compression-dissected from an unfi.xed cell. From left to right, the non-ciliated 'granules' 

 of the ribbed wall complex followed by four columns of the ciliated quadrulus complex and eight columns of the 

 ciliated peniculus complex (26). Phase. 



B. Macronucleus anlage in an exconjugant during extrusion of young nucleoli: net-like figure in the center is 

 fusion product of old nucleoli (15). Phase. 



C and D. Electron micrographs of a similar stage. The smaller dark bodies are chromatic elements of the nuclear 

 matrix: the larger bodies at the left are young nucleoli, and at the right in the cytoplasm are mitochondria (15). 



E. Electron micrograph of a single packing unit of the hexagonal complex of the pellicle system (4iS). Note the 

 cross-sectioned kinetodesmal fibrils in the bays of cytoplasm at each side of thecilium base; at the left, a portion of a 

 trichocyst with its golf-lee-like head: at the right a tubular mitochondrion (S. 9). 



None of these photographs has been previously published. Each is a part of the work cited in parentheses, and 

 done in collaboration with Drs E. L. Powers and L. E. Roth of Argonnc National Laboratory. 



to face p. 224 



