P^rt" l"V Tumors and Organismal Differentials 



Introduction 

 The Nature of Tumors 



In a preceding part we have discussed the organismal differentials and, 

 in particular, the individuality differentials of normal tissues and the 

 reactions they call forth in the host. Under certain conditions normal 

 tissues become transformed into cancerous or so-called malignant tissues, 

 which possess characteristics differing in certain respects from those of normal 

 tissues. It will be of interest to inquire whether in this cancerous transforma- 

 tion the individuality differentials and the organismal differentials, in general, 

 also undergo changes ; but first, we shall state briefly ( 1 ) wherein some of 

 the differences between normal and cancerous tissues consist, and (2) what 

 causes this transformation of normal into malignant tissue. 



In cancerous tissues the growth energy is increased, at first usually in a 

 localized area; but this increase in growth energy differs from the increase 

 observed in embryonal tissue, in that it is not accompanied by progressive 

 differentiation and in that often irregularities in the structure of cells and 

 their nuclei and in cell multiplications take place. Mitoses may be abnormal, 

 amitoses and giant-cell formation may be found. In the actively dividing cells 

 the normal differentiation of cells and tissues may be incomplete, but there 

 are all degrees of this incomplete differentiation. The stimulated cells fre- 

 quently undergo more active movement ; during these movements the normal 

 organization of the tissues may partly be lost. The cells usually penetrate into 

 adjoining tissues, into blood and lymph vessels, and through the circulation 

 they may be carried to distant places and here develop in the form of metas- 

 tases. Cancerous growth is a dissociated growth, in which some of the regu- 

 lative factors normally controlling tissues are no longer effective. To these 

 structural changes correspond certain chemical changes. In the carbohydrate 

 metabolism, enzymatic splitting processes (glycolysis) may predominate over 

 oxidative processes, especially under anaerobic, but also under aerobic condi- 

 tions, and substances such as lactic acid may then be produced in excess. 

 There may be quantitative changes in the distribution of enzymes and vita- 

 mins found in various tumors, on the one hand, and in the normal tissues 

 from which they developed, on the other; but these alterations may vary in 

 direction, or at least quantitatively, in different types of cancer and in dif- 

 ferent species of animals. There may be still other changes, chemical or struc- 

 tural ; however, it is not certain whether these modifications are primary and 

 causal, or whether they are not, rather, the consequences of the cancerous 

 growth. Metabolic or structural abnormalities of a related kind, although 



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