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period, when their development is incomplete, nor yet 

 at too late a one, when it has proceeded beyond its 

 highest point. If we restrict our observations to the 

 time when development is really at its height, a phy- 

 siological type may be found for every pathological 

 formation, and it is just as possible to discover such 

 types for the elements of cancer as to find them, for 

 example, for pus, which, if it be sought to maintain the 

 specific nature of certain formations, is just as much 

 entitled to be regarded as something peculiar as cancer. 

 Both of them stand upon precisely the same footing in 

 this respect, and when the older writers spoke of cancer- 

 pus they were in a certain measure right, inasmuch as 

 cancer-juice is only distinguished from pus by the higher 

 degree of development to which its individual elements 

 have attained. 



A classification of pathological structures also may be 

 made upon exactly the same plan as that which we have 

 already ventured upon in the case of the physiological 

 tissues. In the first place, there are also among these 

 structures some which, like the epithelial ones, are essen- 

 tially composed of cellular elements, without the addition 

 of anything else of consequence. In the second place, 

 we meet with tissues which are allied to those called 

 connective, inasmuch as in addition to the cells a certain 

 quantity of intercellular substance is present. In the 

 third and last place come those formations which are 

 akin to the more highly organized structures, . blood, 

 muscles, nerves, etc. Now, a point to which I must at 

 once direct your attention is, that in pathological forma- 

 tions those elements the more frequently exist, and the 

 more decidedly prevail, which do not represent the 

 higher grades of really animal development, and that, 

 therefore, on the whole, those elements are most rarely 

 imitated which belong to the more highly organized, and 



