THE LEPIDOMAS 319 



In by far the larger number of cases of this order, either the 

 structure of the tumour so conforms to known neoplasms, the 

 origin of which has been traced positively to some glandular 

 organ, that we are convinced that the growth has originated 

 from the inclusion of a portion of such glandular tissue, or we 

 recognize that the growth occurs in some region, in which, during 

 foetal life, there has existed some duct or portion of lepidic tissue, 

 in a region, likewise, in which in the adult we occasionally en- 

 counter the persistent remains of the same. But pathologists, 

 I believe without exception, agree to the sense of this postulate ; 

 we may not know, in all instances, what is the original tissue 

 from which a heterotopic glandular tumour has had its origin, 

 but we are absolutely sure that that original tissue giving rise to 

 a glandular tumour has not been of the connective tissue type. 

 We may, therefore, I think, lay this down with confidence, that 

 tumours in which the cell arrangement is of the lepidic type, 

 presenting columns or groups of cells, devoid of any stroma 

 between the members of these columns or groups, have been 

 developed from one or other lepidic tissue, and not from one 

 of the hylic or pulp tissues. 



4. We cannot, with equal confidence, make the converse 

 statement, that tumours of the hylic type have always originated 

 from hylic tissues and not from lepidic. 



4a. I believe that I am right in stating that lepidic tumours 

 of epiblastic and hypoblastic origin, however rapidly they grow, 

 however extensive and distant be their metastases, always, even 

 in their most aberrant portions, retain lepidic properties. Wher- 

 ever two or three of the specific cells of such a tumour are gathered 

 together, they form alveoli with no stroma and no interstitial 

 capillaries. To the best of my knowledge, no case is on record 

 in which it has been satisfactorily proved that peripheral or 

 metastatic growths of a typical carcinoma of epiblastic or 

 hypoblastic origin have assumed definitely sarcomatous characters. 



Possibly the careful studies now being made in connexion 

 with the melanotic tumours originating in connexion with the 

 skin may prove that this statement will need eventual revision. 

 Authorities are still so much divided as to the exact origin of 

 sundry tumours of sarcomatous type belonging to this group, 

 that it is not possible to make an absolute statement concerning 

 their origin. If, however, it can be proved that under certain 



