TUMORS. 471 



several types of tumors may be combined into what Virchow 

 designates tumors of combination. Tumors may be localized, that 

 is, confined to the production of a single growth in the body ; or, 

 in other instances, several or a number of tumors may appear. 

 In the latter case, all tumors may be produced by the same tissue 

 system j or an originally solitary tumor may become multiple by 

 what is called infection. Infection with the formation of multiple 

 tumors may again be local if the tumors are near each other; or 

 general, if the multiplication is brought about by the infection 

 of different, usually internal, organs, distant from the original 

 seat of the disease. In myeloma the infection is primarily car- 

 ried by the blood-vessels; in cancers almost always by the 

 lymphatic system. 



Benignity and malignity. For a number of years tumors have 

 been divided, according to their clinical features, into benign and 

 malignant. This designation is based upon the nature of the 

 tumors, as well as their clinical course. Nobody doubts that a 

 tumor as such can never be altogether benign, as it always 

 expresses a morbid condition, and tumors of a so-called benign 

 character may produce distressing and even fatal results by pres- 

 sure and tension, atropy of organs, or disturbance of their func- 

 tion. But it is of great importance to preserve the clinical 

 nomenclature, so much the more from the fact that the patho- 

 logical and microscopical features fully agree with the clinical 

 observation. 



Benign tumors are those which appear in most instances as 

 single growths ; if multiple, they arise in the same tissue system ; 

 for instance, many chondromata are found in the osseous sys- 

 tem, many lipomata in the subcutaneous tissue, many fibromata 

 in the skin. They remain local during their entire course, are 

 not infectious, and do harm only by disfigurement, ulceration, 

 pressure, and tension. Such tumors are either composed of 

 simple tissues or combinations imitating the structure of the 

 normal organs. 



Malignant tumors are those which, though appearing originally 

 as single tumors, subsequently, by local infection or by " metas- 

 tasis," i. e., transportation into other organs, become multiple, 

 therefore they are also called infectious tumors. Sooner or later, 

 but invariably, they lead to general disturbances, to a breaking 

 down of the constitution, and to a fatal termination, either by 

 exhaustion, by haemorrhage, or by interference with the function 

 of important internal organs, such as lungs, liver, kidneys, etc. 



