334 LECTURE XIV. 



taking up, when excited by definite stimuli, more or less 

 matter and transforming it. This constitutes at the same 

 time the first step in the most important processes which 

 we have to follow into the domain of pathologico-anato- 

 mical facts. 



A part, which nourishes itself, can in doing so either 

 limit itself to a mere maintenance of its existence, or it 

 may, as is especially seen in pathological cases, take up 

 into itself a larger quantity of nutritive material than is 

 wont to happen in the ordinary course of things. If we 

 investigate these processes of absorption more closely, we 

 always find that, as I have already had occasion to re- 

 mark to you, the number of histological elements remains 

 the same before and after the occurrence of the excita- 

 tion ; and we thus distinguish simple hypertrophies from 

 the hyperplastic conditions, to which, in their external 

 effects, they often bear so great a resemblance (p. 94, 

 Fig. 27, B). It is, however, of extreme importance for 

 the attainment of correct pathological notions, that we 

 should know that a part, which in virtue of some inhe- 

 rent power, takes up a large quantity of material, need 

 not on that account necessarily fall into a permanent 

 condition of enlargement, but that on the contrary, under 

 these very circumstances there often arises subsequently 

 in its internal economy a disturbance which imperils the 

 persistence of the part and becomes the proximate cause 

 of its destruction. There are, as we know from experi- 

 ence, certain limits to the enlargement of every tissue, 

 within which it is able to maintain a regular existence ; 

 if these limits be exceeded, and especially, if suddenly, 

 we always see that obstacles spring up impeding the fur- 

 ther life of the part, and that when the process runs a 

 particularly acute course, a weakening of the part sets 

 in, proceeding to a complete destruction of it. 



Processes of this kind form a part of that domain which 



