334 THOMAS J. HELDT 



pink staining networks become less distinct and in places ill- 

 formed. 



That post-mortem changes have a marked influence on the 

 cytological appearance of the tissue there can be no question. 

 But it is questionable if the post-mortem changes produce alter- 

 ations sufficiently great to be detected by our present technique 

 until a considerable time after death, at least half-an-hour. The 

 relationship between the acid reaction of the neural tissue and 

 the post-mortem changes produced are not so strikingly notice- 

 able as Mollgaard's emphasis on this point would lead one to 

 believe. Mollgaard states that the cerebrum of dog shows a 

 marked acid reaction to moist neutral litmus paper ten minutes 

 after death. It was however fully twenty minutes before the 

 author could be slire of such acid reaction. Nevertheless, it is 

 quite possible that with a more delicate indicator an acid reac- 

 tion might be observed somewhat earlier. 



To determine whether the network could be produced in cells 

 that had first been fixed, some smears were made approximately 

 seven minutes after death, fixed in 96 per cent alcohol at room 

 temperature for one hour, and then subjected to a temperature 

 of — 15°C. At this temperature (which was possibly not low 

 enough) no networks could be observed in the cells. The Nissl's 

 bodies had remained unchanged. This question of the possi- 

 bility of structural change through freezing after fixation, how- 

 ever, was insufficiently investigated to warrant any definite con- 

 clusions; yet, it is a matter of common knowledge that in the 

 use of various neurological methods where the tissue is frozen 

 after fixation no marked changes at least have been reported. 



Smears of fresh hepatic and pancreatic tissues, prepared after 

 the manner of the neural tissue preparations, show networks 

 which are markedly similar to those of the neural tissue, the 

 chromatin of the nuclei giving rise to a blue-staining network 

 while the non-chromatic elements give a pink-staining network. 

 Thus it may be said that Mollgaard's blue-staining reticulum is 

 not a characteristic of neural tissue alone but may be formed 

 from the chromatin of the nuclei of hepatic and pancreatic cells 

 as well. 



