200 GEORGE H. HOGEBOOM AND WALTER C. SCHNEIDER 



formation relating to structural detail has until recently been severely- 

 curtailed by the inherent limitations in the resolving power of the light 

 microscope. It is now apparent, however, that electron microscopy is cap- 

 able of surmounting this impasse to such a degree that structures of molecu- 

 lar dimensions can, at least in theory, be characterized morphologically. 

 The result is that cytology is no longer a static science and that, among 

 other advances in the field, a much more complete picture of the cell cyto- 

 plasm is being rapidly unfolded. 



Concurrently, a relatively new and still somewhat controversial area of 

 research, generally referred to as cytochemistry, has produced a consider- 

 able mass of data relating the biochemical organization of the cell to its 

 structural organization. Like the new cytology, however, cytochemistry 

 is suffering from growing pains in that it is at present strictly in a meth- 

 odological stage and its methods are as yet imperfect. In the present chap- 

 ter, an attempt is made to discuss the uses and limitations of the cyto- 

 chemical technics now available and to summarize the results that appear 

 to be based on sound experimentation. The reader is referred to a number 

 of other recent reviews, ^-^^ either general in nature or dealing with specific 

 aspects of cytochemistry, and presenting, in some instances, points of view 

 different from that of the present authors. 



2. Cytology of the Cytoplasm 



By far the greatest proportion of data pertaining to the biochemical 

 properties of cytoplasmic components has been obtained in studies of 

 mammalian liver. This tissue is convenient for cytochemical investigations, 

 particularly for cell fractionation experiments, because in terms of total 

 mass (see below) it is composed largely of what appears to be a single type 

 of cell containing abundant cytoplasm and readily disrupted by mechanical 

 means without undue damage to the intracellular elements. 



1 A. L. Bounce, in "The Enzymes" (Sumner and Myrback, eds.), Vol. 1, p. 188. 

 Academic Press, New York, 1950. 



2 A. L. Bounce, J. Cellular Comp. Physiol. 39, Suppl. 2, 43 (1952). 

 ' C. de Buve, Exposes ann. biochim. med. 14, 47 (1952). 



* G. H. Hogeboom, Federation Proc. 10, 640 (1951). 



^ G. H. Hogeboom, W. C. Schneider, and M. J. Striebich, Cancer Research, 13, 617 



(1953). 

 8 H. Holter, Advances in Enzymol. 13, 1 (1952). 

 ' K. Lang, Colloq. deut. Ges. physiol. Chem. Mosbach-Baden, p. 24 (1951). 



8 W. C. Schneider and G. H. Hogeboom, Cancer Research 11, 1 (1951). 



9 W. C. Schneider, J. Histochem. and Cytochem. 1, 212 (1953). 



"J. F. Banielli, "Cytochemistry, a Critical Approach." Wiley, New York, 1953. 



1' J. R. G. Bradfield, Biol. Revs. 25, 113 (1950). 



12 H. Holter and K. Linderstr0m-Lang, Physiol. Revs. 31, 432 (1951). 



" B. E. Green, J. Cellular Camp. Physiol. 39, Suppl. 2, 75 (1952). 



