CANCEROUS TUMORS. 27 



transformations about which there can be no question, namely, 

 the occasional conversion of the gland vesicles into C3'sts. 

 But there is another alteration in those of the gland vesicles 

 which are most nearly normal, that can be seen in the sec- 

 tions from which these photographs were taken, and that has 

 been shown in one or two of the photographs ; namely, an 

 increased number of epithelial cells in the interior of the 

 vesicles, so that they form several layers, instead of one, 

 which is all that exists in the normal vesicle.* I am inclined 

 to believe that this increase of the number of the epithelial 

 elements may go on until the vesicles and ducts are so dis- 

 tended by them as to form in fact a portion of the cancer 

 cylinders, "Whether the increase is due to cell multiplication 

 or to the interpellation of wandering Avhite corpuscles must 

 remain for the present an open question ; at all events I find it 

 impossible to admit that the majority of the cancer cylinders 

 have originated either in this way or by the outgrowth of buds 

 from those thus formed. On the contrary the study of the 

 marginal portions of growing breast-cancers inclines me more 

 and more to the opinion that the small-celled brood, accumu- 

 lating in the lymph spaces, is transformed into cancer cylin- 

 ders. That this takes place even in skin cancers I have 

 endeavored to show, and it appears to me that the process 

 plays even a more important role in cancers of the breast, 

 forming probably the greater part of tumors which haA^e at- 

 tained any considerable size, and the whole of those which 

 develop as secondary growths after the complete extirpation of 

 the gland for cancerous disease. 



A study of the mode in which cancers of the breast invade 

 the adjacent fat is very suggestive in this connection, and I 

 will give a short account of the process as I have observed it. 

 The outgrowth takes place in two ways — on the one hand the 

 process involves the fat immediately adjoining the carcinoma- 



*C3tricker'a Manual of Histology. American edition, \>. 577. 



