134 JEREMIAH S. FERGUSON 



cells are frequently seen flattened against the surface of fiber 

 bundles, blood-vessels, or fin-rays, and exhibiting a slow stereo- 

 tropic locomotion. Many of these cells would seem to be identi- 

 cal with those which in stained preparations we are accustomed 

 to call lamellar cells. 



That connective tissue cells exhibit a certain amount of motion 

 is no new observation. It has been well known since the inflam- 

 matory reaction to injury or infection; was studied in the mesen- 

 tery by Arnold and others. I have observed that the extent and 

 rapidity of the motion varies with the cell type. The round cell, 

 or primitive type, presents relatively little motion, it being limited, 

 so far as I have observed, to the very slow projection and retrac- 

 tion of minute pseudopods. Even this evidence of activity seems 

 rather to be limited to those later phases of the cellular stage which 

 foreshadow the transformation of the round cells to the stellate 

 type of the succeeding stage. This transformation is indicated 

 by the fact that the motion is more noticeable near the border 

 of the round cell area than in its interior, and also because at the 

 extreme margin of such a cellular area one may by careful scru- 

 tiny observe an extensive alteration from round to stellate types, 

 some cells passing rapidly to an approximate spindle form. The 

 type of motion exhibited by the round cells, when observable, 

 is well shown by fig. 4, cells a-c being observed at the extreme 

 margin of the round cell area, cells d-e just within the margin, 

 and cells f-g well in the interior of the area. 



While the general trend of cell change is from round to stellate 

 to spindle cells, a change may often be observed to occur in the 

 reverse direction, as occurred to the cell shown in fig. 5, and that 

 in fig. 6. Such retrograde changes are less frequently observed, 

 and the transformation is less extensive than are the progressive 

 changes from the round to the stellate forms. The retrograde 

 stellate phase is also more frequently of a transient character 

 (fig. 5). Thus, a stellate cell may by retraction of its processes 

 temporarily assume a spheroidal form but it soon again projects 

 pseudopods and regains its stellate character. Or a typical, 

 bipolar, spindle shaped cell may extend a third process, or even 

 several additional processes (figs. 2, 5 and 6), but, so far as I have 



