164 M. R. KING 



granular protoplasm of the Purkinje cells as shown in figure 16. 

 Granules are especially pronounced around the periphery of the 

 cells, and they are so closely packed that the outlines of the 

 cells may be followed by merely following the dark band of 

 granules. The dark wavy intercellular substance in many places 

 coincides with the granular layer but is also found in many 

 places where the granular outline is not shown. This is likely 

 due to the inconstancy of the silver reaction. In one place the 

 granules only are stained while in a third place both may be 

 stained together. For demonstration of the intercellular sub- 

 stance of the Purkinje cells it is, of course, necessary to have real 

 fresh hearts. Positive results were obtained only from warm 

 hearts taken directly from the killed animal. 



While injecting one of the preparations with silver nitrate it 

 was found that the sheath had been ruptured while dissecting 

 out the fasciculus, and that a small tag of Purkinje cells entirely 

 devoid of a connective tissue sheath or covering was reflected on 

 the slide. By teasing these cells under low power magnifica- 

 tion with a needle it was found that they broke apart very easily. 

 A few of them were transferred to a second slide and stained 

 with Delafield's haematoxylin. Upon examination with the oil 

 immersion they were found to be polygonal cells with two or 

 more nuclei as shown in figure 14.^ A complete encircling striated 

 border was always present around the peripherj^ of the cells. 

 These striae in many places seemed to cross to neighboring cells 

 joining the striae of the latter, thus resembling the protoplasmic 

 bridges found in epidermal cells. Many of the cells stained 

 with silver nitrate were found to show cross striations similar 

 to cardiac muscle fibres. The centers of the cells are devoid of 

 striations but granules and irregular masses of sarcoplasm are 

 stained by the silver nitrate. One or more nuclei were found 

 in various places in each cell. 



In a few cases the injection-mass was noticed to have entered 

 clefts between the cells as shown in figure 13. The pressure of 



^This conohision harmonizes with that of Ranvier, who obtained similar 

 results after maceration with "potash," but unfortunately Mr. King was unable 

 to investigate this question more fully — -A. W. M. 



