GLANDULAR CELLS OF THE FROG'S PANCREAS 389 



Sjovall's formalin-water-osmium method, Cajal's uranic nitrate- 

 silver method, and Golgi's arsenic method. Of these I have 

 obtained excellent results with Kopsch's, WeigPs, Sjovall's and 

 Cajal's methods, whereas Golgi's method afforded no satis- 

 factory results in spite of repeated trial. In addition, the net- 

 work may occasionally be brought into view by the Flemming 

 fixation and iron-haematoxylin staining. The network can also 

 be exhibited, though in an ill-defined manner, in preparations 

 fixed in Zenker's fluid and stained by iron-haematoxylin (figs. 

 80, 81). 



b. Shape and position. The intracellular network (figs. 

 88 to 96) is situated above the nucleus; it is occasionally placed 

 near the distal end of the cell rather than the nucleus, and 

 spreads to a greater or less extent basalward along the sides of the 

 nucleus. The area which is occupied by the network has all 

 sorts of indefinite shapes and varies greatly in extent. The net- 

 work itself consists of thick or thin cords which ramify and 

 anastomose in various ways. Sometimes the net is not com- 

 plete, so that long or short cords or fragments of the net are scat- 

 tered through the granular zone. In spite of these varieties, 

 there can be seen no intimate relation between the network and 

 the nucleus; they are never in close apposition to, or in direct 

 connection with, each other. 



The network, as seen in a Kopsch preparation (fig. 88), is of 

 compact character, the cords being relatively thick and those 

 projecting into the surrounding plasm being usually short or 

 often lacking. In the remainder of the cell, especially in the 

 basal portion, there can be seen fine filaments or granules stained 

 black and often attached to the network. I am unable to deter- 

 mine whether these structures are to be regarded as consisting 

 of the same substance as the network or as mere precipitation 

 of osmium. 



In preparations made according to Weigl's (figs. 92 to 94), 

 or especially Sjovall's (figs. 89 to 91) and Cajal's methods (figs. 

 95 to 98), the shape of the network, as a rule, is very irregular, 

 extending over a polygonal or elongated area. The most striking 

 picture obtained by these manipulations is that the network 



