326 thomas j. heldt 



nissl's bodies 

 1. In unfrozen smears 



The observations on Nissl's bodies in nerve cells of unfrozen 

 tissue may be verj^ briefly considered. 



In smears not subjected to freezing, but fixed in alcohol at 

 ordinary room temperature the Nissl's bodies are present, clearly 

 and definitely defined in cells fixed twenty-five seconds after 

 decapitation (fig. 2). They were also present at all intervals 

 thereafter until they were finally lost in the complete post-mor- 

 tem disintegration of the tissue. Similarly Nissl's bodies are 

 present, distinctly defined, in the nerve cells of smears placed, with- 

 out the usual fixation, in the toluidin-blue stain one and three- 

 fourths minutes after death. Not only are the Nissl's bodies 

 distinctly present in the foregoing preparations, but also their 

 form and their distribution in the cell body and the dendrites 

 are clearly evident. In some of the best smears, and with good 

 magnification, it is even possible to see that the Nissl's bodies 

 are composed of granules which lie embedded in a matrix, the 

 ^gerinnselartige Masse' of Held ('95). In Nissl's bodies in the 

 periphery of a well differentiated cell this matrix appears of slightly 

 purplish hue while the Nissl's granules are a deep blue. These 

 observations on the matrix are in agreement with those of Held 

 ('95 and '97) and Becker ('06). 



2. In frozen smears 



In the case of the frozen tissue the picture is quite different 

 from that of tissue that has not been frozen, and as an aid to 

 its interpretation a few preliminary notes on the effect of freez- 

 ing on some fluids and fluid-masses may first be mentioned. 



Since such a great percentage of all tissues and fluid masses 

 is water and because so much separates out during the process 

 of freezing, it is of interest to note the appearance of a frozen 

 drop of water or of the ice as it fills the interstices of the tissue. 

 The appearance is one of large and small prismatic and spherical 

 foam-cells (Quincke) filled with clear pure or nearly pure con- 

 gealed water with here and there small air bubbles between their 



