SHORT PAPERS 383 



to convince myself, but without doubt changes in the behavior of the cells towards 

 stains occur, as may be shown most easily in the cancers of the gastro-intestinal 

 tract. Not every phenomenon of growth in preformed epithelium can, however, 

 be looked upon as the beginning of cancerous transformation, for there occurs at 

 the border and in the neighborhood of cancers and of other rapidly growing 

 tumors, cell division, as well as glycogen formation, which are only the expression 

 of purely hyperplastic processes, but when a distinct conical invasion of the under- 

 lying tissues, with transformation of the cell-body, can be demonstrated, we may 

 well think of primary cancerous transformation. 



The origin of cancer cells from preformed epithelium can, of course, be re- 

 cognized most easily in very young cancers and Dr. Borrmann, Ribbert's assist- 

 ant, who collected such cases and investigated them carefully did a great service. 

 In his recently published work he brings proof of the epithelial origin of cancer 

 cells in young primary cancers. 



Secondary cancers of all sorts give especial support to the view that all cancer 

 cells originate from epithelial cells in regular generation; because the numerous 

 mitoses which cancer cells show let us see how rapidly they are divided; so 

 rapidly that the entire growth of these secondary tumors may be completely 

 explained in this way. The occurrence of the first cancer cells in the lymphsinus 

 of the lymph glands, or the appearance of cancer cells in blood-vessels, shows us 

 that metastatic cancer cells are the basis and starting-point of new cancer nod- 

 ules. It can be shown most strikingly by study of serial sections of cancers of 

 embolic origin in the lungs or the liver that cancerous growth in the neighborhood 

 of the vessel always takes its origin from a cancerous penetration of the wall. 

 There is no auto-infection through the uninjured vessel wall of the connective 

 tissues surrounding the walls of the vessel, but a continuous connection between 

 the embolus and the peri- vascular cancer; the embolus by increase of its cells 

 has grown through the wall into the surrounding tissue. 



The behavior of the parenchyma cells at the seat of the new tumor gives 

 especial support to the view that all cells of the secondary cancer have arisen 

 from displaced cells of a previously existing cancer. As we may show especially 

 in cancers of the liver, the local cells, the liver cells, have absolutely nothing to do 

 with the formation of cancer cells. They remain entirely passive, and are pushed 

 aside by the uninterruptedly dividing cancer cells, they become atrophic and 

 finally vanish completely. 



All these facts show that the epithelial cells are the essential elements of cancer. 

 But they are not only the essential but the only essential element. The tissue 

 which in addition is present in cancers, stroma, has no bearing on the nature of 

 cancer. 



There are carcinomatous tumors without any stroma. In the so-called lymph 

 vessel cancers, that is, the growth of cancer cells in the lumen of lymph vessels, 

 as known in cancers of the lungs, of the uterus, and of other parts, extremely 

 dilated lymph spaces can be filled, for long stretches, entirely by cancer cells 

 without a trace of stroma being present. In other cancers the local tissue of the 

 part may take the place of stroma. Thus there are cancerous growths in the lung 

 in which the alveolar lung framework fills immediately the place of cancer 

 stroma. Thus, in intro-vascular or infiltrating carcinoma of the liver, the liver 

 tissue itself, liver cells, and interstitial connective tissue form the stroma. In 

 other cases, however, the cancer stroma is a new formation, as is shown most 

 plainly in many cancers of the ductus thoracicus in which the lumen of the di- 

 lated duct contains not only cancer cells but also stroma, which consists, of course, 

 of completely new formed tissue, but of tissue which has originated from the 

 nearest local tissue, namely, the vessel-wall. 



Professor Williams, of Buffalo, has in my institute at Gottingen studied such 



