The worker in the field of cancer research, apart from absorbing and extending fundamental findings from all investigations on biological problems, has been driven for quite a while to find differences (however small but significant) between embryonic, proliferating or resting normal, regenerating and abnormal tissues. Such knowledge should contribute to the understanding of the nature and the cause of cancer and is a prerequisite for the rational development of carcino chemotherapy. If this student of oncology is a chemist, he will aim at the elucidation of the following problems which, though frequently overlapping, can be roughly divided, as biochemistry as a whole is, into static and dynamic aspects.

He has investigated, and will do so for quite a while to come, the quantitative differences between levels and availability of constituents of tissues, cells and sub cellular particles derived from embryonic, normal and abnormal parts of the body at any time and age and will check his analytical techniques and the choice of base line for his estimation of data as often as possible. The expression 'constituents' refers to the nucleic acids, DNA and RNA, nucleotides, including di- and tri phosphates, nucleosides, purines and pyrimidines; proteins, including lipo- and muco proteins; carbohydrates and derivatives; lipids and phospholipids; electrolytes and trace elements; and particularly from a functional standpoint, to immunobodies, hormones and enzymes (apoenzymes, coenzymes and metal activators).

He will look for qualitative differences between various cell types, 'qualitative' meaning that the level, either de facto or functional, of a constituent X in a special kind of biological material has fallen to zero. This includes therefore the absence, in diseased tissues or cells, of a normal constituent acting perhaps in the healthy parts as a controlling factor of growth and cell division or as an agent influencing properties of cell surface; it also includes the presence in the tumor of a constituent which has never been found in normal tissue.

As there is never a completely steady state of the contents of all these constituents, the whole being in flux during the life time of the cell or its descendants and dependent on their fate, it is desirable to study also the distribution of these components, wherever possible, between membranes, cytoplasm, mitochondria, lysosomes, microsomes, nuclei and nucleoli, chromatin and chromosomes, and to consider the degree of hydration of the whole system. Thus the movement of the constituents between these various parts of the cells brings the chemical student of oncology face to face with the dynamic aspects. There, differences in metabolic processes, anabolic, catabolic or energy producing and metabolic pathways, again between one or the other kind of tissue, will demand his most serious attention. He will search for chemical changes during differentiation, morphogenesis and from embryonic to adult, from resting to proliferating, from normal to precancerous and cancerous tissue, from differentiated to de differentiated cells. Logically he will try to puzzle out the chemical events accompanying mitotic and intermitotic stages of dividing cells and those taking place when subcellular structures are formed or dissolved, including the appearance or disappearance of virus like particles.

Numerous workers have already contributed to the solution of these problems and many reviews have been written on past achievements and future working programs.110 113 117-137-227 But as all these results and plans have to be read in context with those emerging from the biological side,49 51,60,103 one discipline often critical of the other, it is hardly possible to give an adequate list of every major contribution in a preamble to a slender volume.