430 J. A. MURRAY, 



rodlets is seen. They lie in all directions and together constitute the 

 Nebenkern. Similar smaller rodlets lie in the protoplasm, giving it 

 an opaque granular appearance. Material fixed with Hermann's 

 mixture with subsequent pyroligneous acid reduction, gives almost 

 identical results. Fig. la represents a cell from such a preparation 

 in optical section. In Fig. 1 the vertical extension of each apparently 

 independent segment is shown by shading. The rodlets do not dis- 

 appear at once on changing the focus, but undergo a lateral or tor- 

 sional movement : they are not rods but minute scales, the appearance 

 of rods being merely the optical sections of minute curved surfaces. 

 In neither figure has an attempt been made to introduce all the 

 segments visible. Their number is much greater than the twelve or 

 fourteen figured, and is, as Lee notes, about twenty, but it will pre- 

 sently appear why an accurate determination cannot be made. The 

 cytoplasmic rodlets exhibit a similar change of position on changing 

 the focus. 



Fig. 21, which is from an Arion preparation, forms a transition 

 to the appearances seen in Perenyi and sublimate acetic material 

 given in Figs. 3 — 6. Here (Fig. 21) the whole Nebenkern is stained 

 dark brown, the contours are sharp, and the black lines which limit 

 the Nebenkern toward the cytoplasm also alter their position when 

 the focus is changed. In fact they are the optical sections of those 

 thicker parts of the deeply staining shell of the mamillated rounded 

 mass, which lie in the optical axis. From this figure the transition 

 is easy to Figs. 3 — 5, which are from Perenyi (Figs. 3 and 4) and 

 sublimate acetic material (Fig. 5), stained with Bordeaux red and 

 iron-alum haematoxylin. Here the Nebenkern stains more diffusely 

 and seems sharply indented or drawn out into rounded projections in 

 Figs. 4 and 5. Fig. 6 is from a sublimate acetic preparation stained 

 with iron-alum haematoxylin alone. The Nebenkern surfaces are very 

 deeply stained, so that they are visible in surface view, whereas in 

 the preparation from which Fig. I is taken they are invisible in this 

 position. The Nebenkern is thus a mamillated or lobulated body, the 

 only part of which that stains strongly is the thin condensed outer 

 layer or shell, which varies in thickness from place to place. The 

 intricacy of the folding of this outer layer is illustrated in Fig. 2. 

 The Nebenkern has been divided equally and the figure represents 

 the lower half. The cut margin is represented black, and the shad- 

 ing shows the vertical extension. 



Figs. 3, 4 and 5 also show two minute black granules in the 



