TUMORS. 539 



medullary cancer. The pathological significance of these ele- 

 ments differs according to the views of different authors. Those 

 who believe the cancer epithelia to be an offspring of physiologi- 

 cal epithelia, and consider them to have a certain specificity and 

 independence of connective tissue (Thiersch, Billroth, Waldeyer. 

 and others), assume that the medullary corpuscles in the cancer 

 frame are due to an inflammation reactive upon the growth of 

 the epithelia. While Virchow, who maintains a formation of 

 cancer epithelia-from connective tissue, considers these corpuscles 

 as products of the " connective-tissue cells." The following 

 article treats this subject more in detail. 



THE ORIGIN OF THE CARCINOMA ELEMENTS. BY E. W. HOEBER, M. D., 



NEW-YORK.* 



Regarding the origin of the cancer elements, pathologists nowadays hold 

 two essentially different views. Virchow first announced that " connective- 

 tissue corpuscles " might change into epithelial bodies ; while Thiersch, Wal- 

 deyer, and others maintained the view that epithelium is endowed with the 

 property of an independent development ; epithelia of pathological formation, 

 therefore, must always be the offspring of normal epithelia. The followers of 

 the latter view seek support in the history of development, and avail them- 

 selves of the theory of the germinal layers, as established by Remak, for the 

 explanation of pathological occurrences. To-day, arguments of this kind are 

 of little value. The assertions of the independent action of the germinal lay- 

 ers fall to the ground in face of the fact that, before the appearance of such 

 layers, the germ is entirely composed of elements destitute of any peculiar 

 character, and it is not till later that special formations arise from these 

 elements. 



We know that in inflammation the tissue returns to a juvenile condition, 

 and breaks down into the elements from which it had sprung. Elements pro- 

 duce their own kind only when in the embryonal condition. All observers, 

 notwithstanding our limited knowledge as to the cause of the growth of 

 tumors, are agreed that the parent tissue, in which a primary new formation 

 originates, also returns to a juvenile stage or stage of indifference, in which it 

 is capable of producing new elements. These, in further development, give 

 rise to the characteristic tissue forms, which are mainly of two kinds : vascu- 

 larized connective tissue and a vascular epithelium. It has been maintained 

 that the epithelia are always offsprings of the upper and under germinal 

 layer, while endothelia originate from the middle germinal layer, especially 

 from the connective tissue. But even this apparently sharp distinction 

 between epithelia and endothelia will lose its point if we take into considera- 

 tion the fact that both epithelia and connective tissue originate from elements 

 which are morphologically identical. 



Koster has attempted to explain the development of cancers from endo- 



* Abstract of the author's essay, " Ueber die erste Entwickluug der Krebselemente." 

 Sitzungsber. d. Kais. Akademie d. Wissensch., 1875. 



