CHORIO-ALLAXTOIC GRAFTS. 283 



The progamme was suggested by Prof. F. R. Lillie of this 

 laboratory to whom I wish to express my appreciation for many 

 helpful suggestions and criticisms during the progress of the 

 \\ork. 



II. METHODS. 



In the experiments recorded in this contribution, I have used 

 chicks of twenty-four, thirty-six, and forty-fight hours of incu- 

 b.ition as tin- -ource n| material. The- methods of grafting 

 employed are similar to tlmse used by Murphy and Danchakoff 

 \\itti certain modifications developed at thi- l.ibor.uory. An i gg 

 of nine io ten day- of incubation is candlfd ,md the juncture of 

 two of the larger blood \e--els is marked. The -hell i- then -teri- 

 li/ed .nnl .1 -in II window i- rut through it at tin- point with a 

 h.H -k-aw bl.idr. 'I is then rfturned to the incubator \\lnle 



the embryo which i- to furnish the material for the tr.m-plant.i- 

 don is put in physiol - It solution on a warm stage under .. 



binocular dissection mil \>c. l ; or illumi nation, t he light oi a 



i-o-u.itt, nitrogen-tilled tungsten lamp is com cut rated on tin- 

 embryo by a bull's-! MK-nser. All dishes are sterilized in the 



autoclave .md .:11 in-trumrnts are boiled in water. I )i~-c. i in- 



die- whit h h.i\e been -round into fine kni\'f- .tie n-ed in the 

 iper.it ion-. \\'ith tlie-e. tlu- primordium is i-ol.iied .md i- then 

 pi. ned on the . horio .!l.intoi t - nifmbrane as near .1- po ible to 

 tin- jniutiire ot the two vessels noted above. The -hell meni- 

 ie \\liich i- torn -lightly to admit the ti--ne i- repl.u-ed, the 

 shell i- returned and tin- rut edges are -e.iled with p.ir.iltiiie. 

 The egg i- then returned to the iii nb.itor in -neh .1 po-ition th.it 

 the \\indo\\ i- do\\n, SO that the weight of the egg in-iire- the 

 contact of the nieinbratu- and the implanted ti--ne. After 

 twelve hour- lli gf is rotated, and at regular interxal- tli. 

 after rolled as any de\ eloping t-gg. M.ui\ of i he t ran -plant- are 

 -me to have more or le-- mechanical injury, and the time reunited 

 lor their incorp. .r..t i< m \\itliin the membrane of the- ho-t ,md 

 Mib-e(|iK'iu infiltration with blood ve el- mn-t \ary. The-i- are 

 the nio-t im])oriant \ariable- \\ith which the method mti-t cope. 

 After -i\ or -even da\ - the egg is opened and the development of 

 the grafted ti lie i- -uidied macro- and micro-. , ,; .ically. 



