250 



If we wish to be just in our review of the historical progress 

 of our knowledge, we must point out that there exists up to 

 the ])rcsent time only one cell-structure of which the share in 

 the inflammatory new formation of cells has not yet been 

 spoken ; these are the nerve-cells. 



The knowledge of the participation of gland-cells, muscle- 

 oorpuscles, and vessel-walls, in the process of new formation 

 during inflammation, has scarcely lessened the great signifi 

 cance of the connective-tissue substance. Only a share has 

 been claimed for those tissues in the process in which the 

 connective- tissue corpuscles hold the first rank. It is only 

 Cohnheim who excludes them altogether, and we see in his 

 theory simply the extreme reaction from Virchow's older 

 principle. 



Virchow ascribed everything to the connective-tissue-cor- 

 puscles ; Cohnheim everything to the colourless blood-cor- 

 puscles. According to Virchow, form-elements that are not 

 connective-tissue-corpuscles could only vanish in the process 

 of inflannnation. Cohnheim is already tending to a similar 

 conclusion by assigning such a role to the corneal corpuscles. 



Cohnheim 's doctrines have found numerous followers. As 

 a consequence of these it is denied that epithelial cells, liver- 

 cells, and muscle-corpuscles, take any share in the new forma- 

 tions of inflammation. The proof on which these statements 

 have been founded are, for the most part, not backed by care- 

 ful consideration. But it would be equally inconsiderate to 

 ignore such boldly made statements, and not to submit the 

 matter to proof. So it has become necessary to examine 

 anew, in all parts and places, the doctrines of inflammation. 

 With this object I have myself taken up a series of the most 

 important questions, or induced younger investigators to take 

 them up. 



The essays relating to them will be brought before you one 

 after the other, and from these I will proceed to a considera- 

 tion of the general result. 



One of these essays will scarcely seem to find a place at 

 first sight in this plan ; it is that concerning the yelk-cleavage 

 and blastoderm-formation of tlie hen's egg; but tissue- 

 ])athologists have, after Remak's and Thiersh's example, 

 begun to appeal to the principles of the history of development 

 in their theoretical studies. The hen's cg"-^ was selected for 

 ])articular attention, simply because our knowletlge of the 

 development of this was regarded as the most advanced by 

 the best informed of our fellow-workers. In fact, the quan- 

 titative j)roportions in the literature of the subject prove this 

 too. For the purpose of tissue-pathology the history of the 



