THE INDEPENDENT DIFFERENTIATION OF 



I ATKD CHK'K PRIMORDIA IN CHORIO- 

 ALI.ANTOIC GRAFTS. 



I. Tin. KYI . NASAL REGIOX, OTIC Ri <.iox, 



AND Ml -i:\CEPHALON. 

 I I I' ,11 HOADLEY. 



'I HI. H' I! < ATORY. THE UXIVERMIY . ! ( llh \t.O. 



I. hit: 



II. Metl 



ill. I 



i 







i. ... -9 8 



/'.It. i 



IV. I ' 



v. -313 



I. IVIRODUCTIOX. 



Tin- r-iudy >!" thf power of independent growth and diileivntia- 

 tii.ii i.f < -mbi \onir primordia (self-differentiation, R>u\ has been 

 pur-iied l'\ various method-. The experiments on tin- de\ elop- 

 ninn i.f i-olated blastomeres, inaugurated by Ron--.'- -tudv of the 

 , ha\e o.ntnl)! ly to our kim\vK-<]-<' nf the 



l(-.ili/.itii>u "t pot-iui.ilitii-> in rK-.ivage f- 1 More recently, 



-!i^.iii'ii \\tli .mil (littcrciiti.iiinn .f embryonic tissues 



IKTII (Mrrird on \<\ oiln-r iiH-ili.d~. Tin- classical rxprri- 



nu-nt- of Harrison (1907 a, [910 on the embryonic nerve cell 



.imphilii.i ill li uc ciilturi-. folhiwi-d l>v IHIIIHTOU> ^tudir- of otln-r 

 embryonic rll- \<\ H.ini-oii (1912 , l.rwi-, M. l\. .md \\'. II. 

 MI i </, /', etc.)i -"id others, funii-h good examples of the specifi- 

 city and the decree . .f the iiide|>eiidein power of differentiation 

 of the isolated > ells of \.iriou- einl.rxcnic organs. Harri-on 

 (1907 &) and others ha\e .ilso made Mudies of the independent 

 power of growth and differentiation of limb primordia and other 

 part-- of the amphibian larva by a method ha\ing many ad- 

 ditional advantages, that of grafting. The part Mudied was 



281 



