mollgaard's reticulum 335 



The networks in the hver and pancreatic tissues, as well as 

 those of frozen smears of egg-albumen, may also be stained with 

 silver nitrate. 



In corroboration of the foregoing obser\-ations on animal tis- 

 sues it may be mentioned that ]\Iolisch has observed very similar 

 appearances in the freezing of amoebae, fungi, yeasts, and vari- 

 ous algae. Molisch's observations however apply principally to 

 cytoplasmic changes. Equally instructive and showing chiefly 

 the nuclear changes due to freezing are the numerous figures of 

 Matruchot and Molliard ('02) in their work on the influence of 

 freezing on plant cells. 



The observations on the neurolibrillae, like those on the Nissl's 

 bodies, may be considered under two headings; nameh", their 

 presence in the unfrozen and in the frozen cells. The neuro- 

 fibrillae are unquestionably present in the unfrozen cells of smears 

 fixed twenty-five seconds after decapitation and thereafter until 

 lost in the total disintegration of the tissue. Although the peri 

 nuclear network and other finer details of the endocellular neuro- 

 fibrillar structure of the nerve cell (such as may be seen in thin 

 sections) are not visible as such in smear preparations, the neuro- 

 fibrillae are distinctly seen at the origin of the cell processes and 

 an endocellular neurofibrillar network of varying richness is more 

 or less discernible in the cell-body. 



In regard to neurofibrillae in frozen preparations it may be 

 noted that smears frozen at —5° to — 20°C. fixed in 96 per cent 

 alcohol, and impregnated with 1.5 per cent silver nitrate for 

 from nine to twenty-one days, show networks corresponding more 

 or less closely to the networks stained with toluidin-blue and 

 erythrosin. Large numbers of darkly stained nerve fibers render 

 the appearance somewhat difficult of recognition at first sight, 

 especially where the smears are thick. In the larger meshes of 

 these networks lie the nerve cells whose individual reticular 

 structure may or may not be continuous with the walls of the 

 meshes about them. In these preparations, when not too darkly 

 stained, the neurofibrillae are unmistakably present in the nerve 

 cells and their processes as well as in the intercellular nerve 

 fibers. They are well stained and quite distinct. The neuro- 



IHE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 23, NO. 4 



