286 Henry Leslie Osborn, 



coloration bluish from the stain and its nucleus of the usual size 

 and form. The remainder of the cell however is quite diiferent. 

 Two regions can be distinguished, an outer one subdivided into 

 four almost separate parts and an inner region not divided but still 

 containing several nuclei. The outer subdivisions have much the 

 appearance of cells, each having its own centrally located nucleus, 

 but each one of these divisions is continuous with the substance of 

 the deeper part of the cell. There are three nuclei in the sub- 

 stance of the deeper part of the cell. These are surrounded by a 

 small amount of fibrous material, which is stained bluish, which 

 radiates out into the brown substance. 



The most satisfactory interpretation of the place of these cells 

 is to regard them as belonging a degree lower down in the series 

 than the giant cell. That cell, see Fig. 16, gives evidence of having 

 been formed from several cells, as shown by the nuclei scattered 

 about in its secondary substance. This cell is quite evidently a 

 cluster of four cells of the type of Fig. 12 which are being incor- 

 porated by an older cell in which the nucleus has become excentric. 

 It would be impossible to suppose that cell no. 15 is a later stage 

 than no. 16 and it does not seem necessary to suppose that they 

 are differentiations along different directions. These sub-cuticular 

 cells thus show marked activity in the work of fixing and retaining 

 a certain substance. 



This process of storage is not confined to dorsal sub-cuticula 

 but takes place though in milder degree in other locations. Thus 

 in the sections of the ventral sucker (see Fig. 9) there are many 

 cells which are much enlarged by deposits of material which has 

 the same appearance as the stored substance of the cells of the sub- 

 cuticular layer. Certain cells, indicated by the letter x in Fig. 4, 

 form a peculiar cluster surrounding the short passage from the 

 excretory bladder to the exterior. These cells to contain some of 

 this material. And even in the testis cells containing it can be 

 recognized. 



It has not been possible to make any positive determinations as 

 to the chemical nature of the substance stored in these cells owing 

 to the impossibility of access to supplies of living worms. Efforts 

 to study this point upon specimens after fixation and sectioning 

 yielded only unsatisfactory results, since the tissues had previously 

 been exposed to so many reagents. A few experiments were made 

 however, the results of which will now be given. The method 



