Loxogenes arcanum Nickerson. 283 



from cells. It is merely an open network of fibres filling in the 

 spaces among the organs and only rarely includes in its meshes 

 the characteristic angulated parenchyma cells. In marked contrast 

 with this is the zone just below the surface where the "sub-cuti- 

 cular" cells form a close and continuous layer, located just below 

 the body-wall muscles. 



The detailed cytological appearances of the sub-cuticular cells 

 are very different in sections of pyloric-cyst worms from those found 

 in worms taken from the urinary bladder. Fig. 10 is drawn from 

 a section from one of these bladder worms. The cells are shown 

 highly magnified in 11 and may be compared with those in 

 Figs. 12—16, all having been magnified to the same scale. It is at 

 once apparent that in the cells from the pyloric-cyst worms there is 

 evidence of activities of a sort which are not taking place in 

 the cells of bladder worms. They are thus in a resting stage. 

 These resting cells will receive attention first. 



A majority of the cells, as shown in Fig. 11 are small. Among 

 them there are a few much larger cells, of difierent form and having 

 a different affinity for stains. The small cells are the chief cells: 

 of the layer, as one can readily see in Fig. 10. Some of these cells 

 have a diameter of 0,01 mm, many others are smaller than that. 

 Their contours are rounded. It is impossible to recognize a wall 

 on the* free surfaces of these cells, but a faint line can be seen 

 between them where they touch each other. Their cytoplasm is 

 clear and stains only very faintly. The nuclei measure 0,005 mm 

 across, they contain a large nucleolus and fine grains of chromatine. 

 Occasionallj" cells can be seen among these chief cells, in sections 

 from the bladder-worms, which exceed the size of the cells just 

 mentioned, but which have their characters in other respects. One 

 of these is shown in the upper part of Fig. 11. 



In addition to the chief cells, the sub-cuticular layer in bladder- 

 worms, contains the large cells, these are cells of a different type 

 which corresponds in every way with the true parenchyma cell. 

 They measure often as much as 0,03 or 0,04 mm in length. Their 

 outline is variable: some are globular, others are elongate and 

 angular. There is no well defined wall. The cytoplasm is richly 

 impregnated with coarse granules which show a strong affinity for 

 iron-haematoxylin, the processes of the cells are clear and faintly 

 stained. The nucleus is very large measuring 0.01 mm and is clear, it 

 contains one large and conspicuous nucleolus but no chromatine. As 



Zool. Jahrb. XXXVI. Abt. f. Anat. 19 



