334 C. M. JACKSON 



7. Pathological conditions (thyroiditis, exophthalmic goiter, 

 etc.), probably due to infections. 



8. Results of imperfect fixation. 



9. Post mortem changes (due to mechanical injury, post mor- 

 tem autolysis, etc.). 



To this should be added the statement that very similar cell- 

 changes have been described, especially by pathologists, in vari- 

 ous tissues of the body, most frequently in the epithelia of the 

 various parenchymatous glands. Changes in the renal epithe- 

 lium following ligation of vessels, infarcts, intoxications, infec- 

 tions, post mortem changes, etc., form a familiar example, in 

 which the phenomena are in many respects strikingly similar to 

 the degenerative changes above described for the thyroid gland. 



The remarkable similarity in the degenerative changes thus 

 found in various organs and under apparently widely different 

 conditions naturally raises the question as to whether the under- 

 lying fundamental process may not be at least in some respects 

 essentially similar in all cases. It may be possible, for example, 

 that cellular inanition may be produced in different ways, and 

 may therefore be the essential factor in the process of degenera- 

 ation arising from varied causes. If, as is now generally as- 

 smned, cellular metabolism is accomplished by means of nu- 

 merous varieties of intracellular enzymes, one could easily under- 

 stand how anything which would destroy or interfere with the 

 activity of any of the enzymes necessary to anabolism might 

 thereby produce a condition of cellular inanition, even in the 

 presence of an abundant food-supply. The probable importance 

 of autolytic enzymes in the phenomena of cell-degeneration, es- 

 pecially in the nuclear changes of pycnosis, karyolysis, etc., has 

 been emphasized by Wells ('14) and others. A final solution of 

 the problem is impossible at the present time, on account of our 

 scanty knowledge of normal cell-physiology; but it seems prob- 

 able that many of the phenomena of cellular degeneration from 

 various apparent causes will ultimately be explainable as due 

 essentially to cell-inanition. 



