mollgaard's reticulum 317 



pieces of tissue are fastened to the object carrier of the micro- 

 tome. The 'inner vessel of the calorimeter' containing the fix- 

 ing fluid, generally 96 per cent alcohol, which by the addition of 

 carbon dioxide snow has been reduced to a temperature of —15° 

 to — 35°C., according to the desired thickness of the subsequent 

 sections, is now brought up about the tissue block. At the 

 appropriate temperature sections are cut with the specially con- 

 structed microtome into the cold fixative. The sections are thus 

 fixed at once and at a low temperature. The fixative with the 

 contained sections is now allowed gradually to acquire room 

 temperature, after which the sections are studied in the unstained 

 condition, or stained with toluidin-blue or nile-blue base. 



After a study of the sections, obtained and prepared according 

 to the foregoing technique, Mollgaard concludes: 



Firstly, concerning the Nissl's bodies: 



1. " Nissl-Korner existiren nicht in vital fixierten Nerven- 

 zellen." 



2. '^Nissl-Korner sind Kunstprodukte, hervorgerufen wahrend 

 der Alkoholfixation." 



He notes, however, that it is not the alcohol alone that pro- 

 duces the Nissl's bodies, for by his method of Vital fixation' he 

 excludes a factor which is present in the usual Nissl's method, 

 namely, post-mortem change. Since he has observed that the 

 first result of post-mortem change is the production of a mesh- 

 work^ in the unstained protoplasm, and a later result that of 

 an aggregated or conglomerated meshwork ('zusammengeballtes 

 Maschenwerk') in the stained protoplasm, he holds that the 

 Nissl's bodies are due to the simultaneous action of post-mortem 

 change and alcohol fixation. He regards the post-mortem changes 

 as acid in character, stating that: "Die Nissl-Korner sind darum 

 als Kunstprodukte anzusehen, und zwar als solche, die durch 

 eine Verbindung der sauren postmortalen Spaltung und der lang- 

 samen Alkoholfixation entstanden sind." 



^ This meshwork, however, seems to be practically identical with the 'glia- 

 network' (to be described later) which Mollgaard finds in his 'vitally fixed' nerve 

 cell, and which he considers normal. Regarding this and some other points his 

 various statements seem vague and inconsistent. 



