10 THE TONER LECTURES. 



considei'ation of epithelial cancer of the skin, and alveolar 

 colloid of the stomach, but he suggests the view that other 

 forms of carcinoma and sarcoma have a similar origin. The 

 consideration of these forms was postponed to subsequent parts 

 of his work, which have not yet been published. 



The opinion of Koester that the cells of the cancer cylinders 

 are derived from the endothelium of the lymphatics has not 

 been favorably received by the majority of histologists, and 

 I believe pretty much every one who has tried the action of 

 silver in cancer sections after the manner he directs has failed 

 as yet to reproduce the appearances on which this portion of 

 his doctrine is based. That the net-work of cancer cylinders 

 corresponds to the lymphatic passages ; that in fact the c}'!- 

 inders, whatever their origin may be, lie in the l3nnphatics and 

 extend in them, appears to be more generally accepted, and I 

 must avow that it is in strict accordance with all I have been 

 able to observe. 



In April, 1870, a paper entitled "A Contribution to the His- 

 tory of the Development of Carcinoma" was published in Vir- 

 chow's Archiv * by Dr. A. Classen of Rostock. It was based 

 on the stud}^ of a case of epithelial cancer of the cornea and 

 sclerotic. It had occurred to the author that the cornea, 

 which had already offered so excellent a field for the study of 

 the inflammatory processes, was also especially suited for the 

 study of the mode in which cancerous growths are developed. 

 He arrived at conclusions very different from those of his 

 predecessors. For him the cells of the cancer cylinders, and 

 indeed all the new elements of cancerous growths, are no other 

 than migrated white blood corpuscles escaped from the blood- 

 vessels after the fashion first pointed out by Cohnheim. 



He calls attention to the rich development of blood-vessels 

 around cancerous growths, and to the comparative sluggishness 



* Vivcliow's Archiv, Brt. 50, S. 5(i. Ueber ein Cancroid der Cornea und Sclera, 

 ein Beitrag zur Entwicklungsgeschichte der Carcinome. 



