TISSUE DIFFERENTIA!!' >N AND RATE OF GROWTH. 2OI 



The fir-t -i-n of extension of the nerve o-nl <OU-JM- in a com- 

 paratively loose mass of nerve cell- or nuclei at the extreme end 

 on the fir-t day. These have -ome appearance of miration. 

 Little difference appear- on the -econd day although a distinct 

 lengthening of the cord has taken place. The third day shows 

 rlv a half millimeter of regenerated n<-r\e cord hut the end 

 -hou- no very detinite -i-n of rapid growth. After that the 

 condition c.mnot be distinguished from the ordinary. 



The noioc hord -hou- some reneual in one day and a -li^hl 



literalion on the 3( < "iid after which it appear- normal except 



for a \er\ -mall area .it the end \\liich retain- the proliferating 



charai ter. I hi- i- true till ahout the fifth day \\hen the di-tal 



OIK- h. ill to t hit c-ii. urth- of the notochi.rd is markedly different 



in .!]! " I'Mii the re-t. The I'ell- are -mailer and n. 



-lion^K -tained. c\cn tl- -pla-m taking tin- ha-!nat"\\ lin 



-lain -li^hiK ' I -tlldy of the >lide indicate- that thi- 



di-ial p.n i oi i!i hord i-inatran-ition.il- dil'leivn- 



li.tiion and that it ha- ap; l'\ ,i -imultane. m- change in the 



neu cells dc-tined t<- l-iriu the di-tal not.ichord. It i- inien -li 

 to note that uh> ys tlu- noiochord had 



hehind tin i : it quickly became .-tc|-minal \\ilh and 



:idcd -liv;htl\ l'e\ond the ner\ i . .rd li\ the ti^hth or 

 ninth da\ . lli: iiotiichord de\ elopmnit i- \ 



-lion-! int ident \\itli the period test 



dini atiou. 



The In-l -ivii o| nui-cle de\ elopnient i- found on the -ixth 

 da\ ulien in i ell ma--e- ai- ni/alile a- aiila^eii i .| the 



neu mu-cle ti--ue I di-lini;iii-hal>li- thn>u;Ji al-oin 



one-half the extent .i| lieu tissue. < >ll the -eXelllll d.l\ a leU 



pi-'ximal >trand- ol uiu-cle -ho\\ fair de\ elopmi-nt . And on ihe 

 eighth da\ -mne are found throughout tin- |>ro\imal third. In 

 nine da\- a leu \\ell de\el..ped lil.er- are di-t in^ui-haMe half 

 u.i\ out in tlu-jieu ti lie an<l on tlu- tenth day it i- extremely 

 ditlicult to ideiitil\ the 1 mrder line lielueen the |iroximal 



neraled mu-cle and the old tisSUi 



While mo-t of tin- tissues -tudied reach tl inal State ot 



de\elopment too -0011 to -ho\\ an\ connection \\ith or inllueiu.- 

 upon tin- lii^he-t -peeil of iv-eiiera t ion iCharl II.', it should he 



