386 HAL DOWNEY 



variable in size and shape. Vacuoles and small spaces are nearly 

 always present, even in the thinner portions of the hypodermis 

 (figs. 1 and 4). The nuclei all have about the same relative 

 amount of chromatin, but their size and shape is subject to great 

 variations. They may be round, irregular or oval, and their long 

 axis may be in any plane. Very large nuclei are shown in figure 



3 behind the tendon fibrils and at the right of figure 4, and figures 

 1 and 2 show the irregularities in the shape of the different nuclei. 



Everywhere the hypodermis contains may sharply defined; 

 homogeneous fibrils which take a wavy course theough the syncy- 

 tium, usually extending through several cell-territories. Sometimes 

 they unite into bundles (fig. 1), but usually each fibril is indepen- 

 dent. They show a general tendency towards an oblique course 

 through the syncytium from its outer to its inner surface, or they 

 may converge on the muscles, as is seen in figure 1, where the 

 fibrils of the syncytium are all directed towards a small area 

 on the bundles of striated muscle fibers shown in the lower right- 

 hand portion of the figure. Occasionally, the fibers will run for 

 some distance in the horizontal direction parallel to the outer sur- 

 face, before they take the oblique course downwards to join the 

 fiber bundles in the basal region of the syncytium (fig. 4). Figure 



4 also shows considerable variation in the size and direction of the 

 fibrils. In the upper right hand portion of the figure one sees many 

 exceedingly fine fibrils whose course is more vertical than that of 

 the other fibers. Some of the thicker fibers permit a considerable 

 change of focus before they pass out of view, which indicates 

 that some of them are bands or membranes and not fibers. 

 Figure 2 shows a very interesting arrangement of the hypodermal 

 fibers. If we examine the bundle of fibers in the basal portion of 

 the hypodermis we notice that one fiber leaves this bundle, and 

 if we follow it to the left we see that it gradually gets further 

 away from the basal bundle until it very suddenly changes its 

 direction. It passes upwards, bends around a hypodermal nucleus 

 and can then be followed back to the right in the horizontal plane, 

 where it is joined by several other fibers running in the same direc- 

 tion, some of which again pass downwards to join the basal 

 bundle. That portion of the hypodermis which is some distance 



