LIVING CONNECTIVE TISSUE CELLS 135 



observed, such processes are limited in size and usually of short 

 duration. This reverse transformation may be likened to an elas- 

 tic rebound brought about by an inherent resistance to change of 

 form reacting against an impelling force which directs the trans- 

 formation from the round to the spindle type. The cell frequently 

 balks at the change, but the general trend from round to stellate 

 and from stellate to spindle form is inevitable. 



Motion resulting in change of form is perhaps most active in the 

 stellate type of connective tissue cell. The general trend of this 

 motion seems to be indicated in fig. 5 /, in which a typical round 

 cell selected for observation at the margin of the round cell mass 

 in a pectoral fin of a 6 mm. embryo was seen within a period of 

 six minutes to elongate and then to pass through successive stel- 

 late shapes to a typical spindle form. But the succession is not 

 always so rapid. Stellate cells exhibit all sorts of morphological 

 transformations in rapid sequence (fig. 7) and this stage of con- 

 nective tissue development is of relatively more transient duration 

 than either the preceding or the succeeding stage. Moreover, the 

 shape of the cell is undoubtedly influenced to some extent by 

 its surroundings and the duration of a particular stellate, spindle 

 or lamellar shape may in some cases be thus determined. 



Likewise, spindle cells undergo considerable transformations 

 in form, the most frequent of which undoubtedly result in the 

 lamellar shapes on the one and in the stellate on the other hand. 

 Because of the limitations of the microscope in the delineation of 

 the 'third dimension' it is most difficult in the colorless living 

 tissues to differentiate between the lamellar and spindle types of 

 cell but the evidence of fixed and stained tissues shows the lamel- 

 lar to be the more mature, the spindle the earlier type, and I 

 have observed nothing in the living tissues to indicate the con- 

 trary unless indeed it be that both types appear to be somewhat 

 dependent on their surroundings, for as already stated these forms, 

 in the same cell, seem to be more or less interchangeable. That 

 spindle cells frequently and freely revert to the stellate type there 

 is abundant evidence. There is also evidence that these cells may 

 be capable of still further transformations than those of mere form. 

 A syncytial stage in the development of connective tissue has 



