512 LECTURE XX. 



different tumours which you can distinguish from other 

 tumours of the same genus by means of the addition 

 "colloid.' 7 You may therefore say : colloid cancer, col- 

 loid sarcoma, colloid fibroma [fibrous (connective-tissue) 

 tumour]. Here colloid means nothing more than jelly- 

 like. Or you must have a distinct notion of the nature, 

 of the chemical or physical peculiarities of the colloid 

 substance, or of the morphological nature of the colloid 

 tissue, and then it will be impossible for you to class 

 together two, chemically and morphologically, entirely 

 different products, such as the colloid of the thyroid body 

 and colloid cancer. 



In just the same manner we see that a great number 

 of tumours, when they are seated on the surface, give 

 rise to excretions, which, according to the nature of the 

 surface, appear in the form of villi, papillae or warts. All 

 these tumours may be comprised under one name and 

 called papillomata, but the tumours which have this form 

 often differ toto coalo from one another. Whilst in the 

 one case we have a true hyperplastic development, we 

 find in another, at the base of these villi where they rest 

 upon the skin or mucous membrane, some specific form 

 of tumour. In many cases even the villi themselves are 

 filled with a substance analogous to that of the tumour. 

 This is a very important difference. If, for example, you 

 examine a broad condyloma, the mucous tubercle or 

 plaque muqueuse of Ricord, you will find, under the 

 epidermis which still remains smooth, the papillae enlarg- 

 ing and ultimately growing out into branched figures so 

 as to represent regular trees. Cancer, however, may give 

 rise to excrescences of the same shape as these condy- 

 lomata. This we see comparatively less frequently occur 

 on the skin than on the different mucous surfaces. In 

 these cases it may happen that real cancer- is seated in 

 the villi. Nor is -this in itself indeed at all surprising 



