mollgaard's reticulum 329 



the more liquid frozen matrix or ice, while the network itself 

 consists of the more solid portions of the tissue. In many places 

 the largest of the nerve fibers found in gray matter appear to 

 form initial strands upon which the network is formed, in other 

 places however they extend into or through the lacuna-like spaces 

 quite unaccompanied by other neural elements. Regarding the 

 various kinds of cells (nerve cells, blood cells, and glia cells) 

 nothing can be made out with certainty in these frozen and 

 unstained preparations. 



Molisch ('97) has shown that the reticulum produced by freez- 

 ing in such colloids as gelatin and starch-paste is more or less 

 permanent after thawing out, others such as gum tragacanth, 

 gum arable, and egg-albumen the reticulum disappears quite 

 completely. The author's observations on the last named col- 

 loid confirm this statement and so too for the non-fixed neural 

 tissue described above no noticeable trace of the effects of tlie 

 previous freezing can be noted after thawing. 



b. Frozen, fixed, and stained smears considered as a whole. 

 Smears frozen, fixed and stained according to the directions given 

 under the heading 'Material and technique' show, when frozen 

 at a temperature of -5° to -10°C., the first effects of freezing. 

 Like the fresh, frozen, unfixed, and unstained smear, the prep- 

 aration, when looked upon as a whole, appears to consist of a 

 more or less coarse network or reticulum the interstices of which 

 are of variable size and form. With greater temperature reduc- 

 tions (-10° to -40°C.) this network becomes more definite and 

 distinct, and presents a number of special features which will 

 be discussed under other headings. The network observed is 

 stained in part blue (by the toluidin-blue) and in part pink (by 

 the erythrosin). Coarse and fine nerve fibers and blood capil- 

 laries lie, apparently unaffected by the freezing (at —5° to 25°C.), 

 surrounded by the network. The pink stained portion of the 

 reticulum appears to be composed of the most delicate nerve 

 fibers and condensations, as it were, of the tissue fluids; in fact, 

 it may be regarded as being composed of all the acidophilic sub- 

 stances of the tissue. The blue stained portion, on the other 

 hand, may be looked upon as composed of the basophilic sub- 



