HISTOGENESIS OF CONNECTIVE TISSUE. -75 



Ha," for the former undoubtedly arises in exactly the same 

 manner as the ordinary "white fibers," and of the histogenesis 

 of the latter little or nothing is known if, indeed, it can be con- 

 sidered as an entity distinct from the other connective tissue 



tiliers. 



The numerous theories which have been proposed to account 

 for the origin of the connective tissue fibers may be reduced to 

 three chief divisions: 



i. The embryonic connective ti--ue or mesenchymal cells 

 !.(((. me directly Iran-formed by elongation into connective 

 ti.ue lib. 



J. Tin- tibi r- arise in the .unmix! -ub-tance betueen the 

 cell- eitlit-r by i rail-formation of that Around -ub-t.mce or a- 

 .1 -' < n lion from ;ln- .idiai < in i <-\\>. 



v Tin- liber- ari-e \\ithin the cell- either a- di-tinct fib 

 - 'lu.mn. i- -mule- \\hich fn-e to form liber- iS|)iiler. 



l6j I.axini, [909 . as an epicellular protopla-mic libroii- layr 



I \ iff, [889 , or as an ectoplasm about the cell I Ian-en, i - 



or forming the -\ iicytiuin Mall, i 



The ihe<,ry of dire, t trail-format inn by elongation of cell- 

 into hber- max \\ell be abandoned ami, except il be con-trued 

 aliuiLi ihe line- of the \aiioii- theori--- o| int racellular origin, 

 it i- \\nrth\- only of pa--iir^ notice. . \nion- other tiling- the 



existence oi an overwhelming num!er of fiber- r<-lati\e to the 



Illllllbl I of i ell- ple-ellt ill Cop llei 'I i \ e ti--lle at'Vlle- ajaifl-t 



dire, i transformation, and mod.-ni mii-ro-coiical meihoil- arc 

 not able to detect tin- pi uch t rail-format imi either in 



normal growing ti lie- or in the p ..I uomul re|.iii. I'or 



Several decade- the re-lilt- of ob.-er\ at ion- ha\e been ill -llpport 

 of eiiher the iniei < ellnlar or t In- int ra< vllnlar -ronp of theorie-. 



To Hellle I^}I we OWe ihe theor\- of the intercellular 



lacellnlai origin of coimei li\e ti lie fiber-, the liber- bein- 



-uplio-ei| to ari-e Irom the intercellular ground -ub-taiice. not 



directly from the cell-. Latterly thi- the..ry ha- received but 



little support mile-- it be from the <>b-ervation- ,,\ Merkel 



[895 . uho found that in the umbilical cord liber- appear lir-t 



to ari-e in location- relatively remote from the cell-. Later 



the cell- \\andered into the-e tibroti- area-, and at a -till later 



