828 



SCIENCE. 



[N. S. Vol. V. No. 12&. 



defects in the tissues, and in interpreting the 

 growth as for the purpose of regeneration 

 or filling up a defect? Differences of 

 opinion upon this subject are illustrated 

 by the different interpretations of the cell- 

 proliferations in acute and chronic inflam- 

 mations ; some pathologists considering 

 these to be essentially regenerative and 

 compensatory ; others regarding them, at 

 least in large part, as directly incited by 

 inflammatory irritants and not to be ranked 

 wholly with the regenerative processes. 



The doctrine of Virchow was long ac- 

 cepted without question, that inflammatory 

 cell-growth is the result of the action of 

 external stimuli, the so-called inflammatory 

 irritants, upon the cells, which are thereby 

 directly incited to grow and multiply. The 

 attack upon this doctrine has been led most 

 vigorously by Weigert, who denies abso- 

 lutely the power of any external agencies to 

 stimulate directly cells to proliferation. He 

 considers that to concede such a bioplastic 

 power to external agents is equivalent to 

 the acceptance of a kind of spontaneous 

 generation of living matter. 



Weigert's views upon this subject have 

 had undoubtedly a most fruitful influence 

 upon pathology. It has been such an in- 

 fluence as a good working hypothesis, 

 whether finally demonstrated to be true or 

 not, has often had in the development of 

 science. In putting to the test of actual 

 observation "Weigert's hypothesis we have 

 been led to recognize the frequency and the 

 importance of primary injuries to cells in- 

 flicted by external agencies. Not only 

 various degenerations and necroses of en- 

 tire cells, but more subtle and partial dam- 

 age of cytoplasm and nucleus, have been 

 made the subject of special study. It has 

 been recognized that our older methods of 

 hardening tissues reveal often only very 

 imperfectly the finer structure of cells, and 

 new and better methods have been intro- 

 duced which enable us to detect more deli- 



cate lesions of cell-substance which for- 

 merly escaped attention, as is well illus- 

 trated in recent studies in neuropathology. 

 "Weigert's postulate of some primary in- 

 jury to the tissues as the immediate effect 

 of mechanical, chemical and other external 

 agencies, which were formerly regarded as 

 the direct stimuli of cell-growth and multi- 

 plication, has been fulfilled in many in- 

 stances where such damage had previously 

 been overlooked or unsuspected. It is his 

 belief that in cases where we cannot now 

 detect such primary injury more thorough 

 search and better methods will enable us 

 to do so. One may, of course, reasonably 

 cherish such an expectation ; but at the 

 same time we must recognize the fact that 

 morbid cell-proliferations occur under cir- 

 cumstances where we cannot at present as- 

 sociate them with any demonstrable pri- 

 mary injury to the tissues — indeed, in some 

 cases where our insight into the structure 

 of the part seems to be so clear and satis- 

 factory that one is very reluctant to admit 

 the existence of an undetected damage to 

 the cells. 



Perhaps the most important modification 

 of former pathological conceptions, result- 

 ing from the belief that cell-growth is 

 caused by primary defects and injuries of 

 tissue, relates to the chronic interstitial in- 

 flammations or fibroid processes. The older 

 view that in these processes the active and 

 essential feature of the disease is the new 

 growth of connective tissue, which strangles 

 the more highly organized cells of the part, 

 has been replaced to a large extent by the 

 opinion that the primary and most impor- 

 tant lesion is the degeneration, atrophy or 

 necrosis of the more specialized cells, whose 

 place is taken by the new growth of inter- 

 stitial tissue. In many instances, as in 

 fibroid patches in the myocardium, and in 

 many scleroses of the central nervous sys- 

 tem, this latter conception affords the best 

 and most natural interpretation of the facts. 



