346 THOMAS J. HELDT 



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PLATE 1 



explanation of figures 



Figures 2 to 6 were all drawn with the aid of a camera lucida. Figures 2 to 5 

 are anterior horn cells of spinal cord of the dog, from smears fixed in 96 per cent 

 alcohol and stained with erj^throsin and toluidin-blue. In the case of the frozen 

 preparations only the blue-staining reticulum is represented, with this exception, 

 that in figure 5 a small portion of the pink-staining extracellular reticulum is 

 represented to show its continuity with the blue network. The individual dif- 

 ferences will be noted in connection with the separate legend for each figure. 



2 Anterior horn cell of an unfrozen smear, fixed twenty-five seconds after 

 decapitation. The Nissl's bodies are distinctly present. Magnification 750 

 diameters. 



3 Anterior horn cell, frozen and fixed at about — 20°C., seventy-four seconds 

 after decapitation. The figure represents one of the early transition forms, the 

 Nissl's bodies appearing as minute networks loosely joined together. Magnifi- 

 cation 750 diameters. 



