2/8 JEREMIAH S. FERGUSON. 



the exoplasm in order to account for the transference of fibers 

 from a position within the cell, in the- ectoplasm, to an extra- 

 cellular position. This hypothec- i- entirely harmonious with 

 i lu- appearances to be observed in "fixed" tissue with the methods 

 used. Ho\\e\vr, it is open to two objections, viz., the obser- 

 vations of Spuler, confirmed in a casual and not wholly satis- 

 factory way by Livini, that fibers actually lie within the cells, 

 and not always at the periphery, as Hansen's and Mall's theories 

 presuppose, but even in direct contact with the nucleus; and, 

 secondly, if the cells are in active amoeboid motion, with loco- 

 motion as well, as is certainly the case in the fins of the embryo 

 Fiunliilns, then one can hardly conceive that the more or less 

 fixed syncytium described by Mall, whose observations can be 

 readily verified by any of the usual histological methods applied 

 to the tissue used, is sufficiently stationary to permit the retrac- 

 tion or shrinkage of endoplasm, thus leaving the endophismic 

 fibrils outside the bounds of the cellular protoplasm, for according 

 to Mall's theory true cells are lost, being replaced by nucleated 

 endoplasmic areas anastomosing with their neighbors to form a 

 continuous syncytial net. 



1 have many times observed the fins of Fiiuditlns embryos 

 between the lengths of 4.5 mm. (at the time of hatching) and 

 25 mm., the pectoral and caudal fins being usually selected, and 

 in no single instance have I observed either a stellate or a spindle 

 cell which did not exhibit changes of form and locomotion, the 

 latter being sometimes very limited, at other times, as shown 

 in Fig. 2, quite extensive. Hence the ultimate theory of con- 

 nective tissue histogenesis, it would seem, must take into account 

 the relative activity of the mesodennic cells. So far as I ap- 

 preciate them, none of the theories thus far advanced fully 

 meet all of the olerved conditions. Further studies of both 

 living and "fixed " tissue may further elucidate the true conditions 

 involved in the histogenic process. 



The fins of living fish embryos offer for the development of 

 connective ti-^ue a most desirable subject for study, for in the 

 subcutaneous tissue betueen the dermal fin-rays one finds a 

 definite connei li\e ik-ue area, in which, with the exception of 

 the >ome\\ hat related chromatophores, there is no other structure 



