CHORIO-ALLAXTOIC GRAFTS. 297 



taining a few cell bodies which correspond to the pear-shaped and 

 spindle-shaped nerve cells of Disse, run to the forebrain where 

 their course is lost in the disorganization present there. The 

 round primordial nerve cells of the nasal epithelium occur 

 in the liber bundle- at rare intervals. The development of the 

 nerve com-pond- '" thai "f the embryo . .f seven >f incuba- 



tion as de-cribed b;. 1 



The l"<irebr..in of the -raft has no limiting membrane. The 



character of the cells is undoubtably that of brain cells but they are 



unorgani/ed. Tlii- rs to be due to the fact that thi-ti-- lie 



Pensively intiltr.ited with blood ve--el-. In places there 



i to In filled with bl 1 cell-. Ntimer- 



-ii). ill nerve-lik. found in thi- region which 



formed by union of the groups of the nerve pi They end 



bluntly and blindh M netrating the nu-eiichyme for -hort 



di-' . inbliii^ -imilar structures found in graft- of the 



im 'haloii which will be discussed below. 



The cartilage \\hich -tirroiinds the nasal sao has been men- 

 tioned above. Th: ge is in a single large piece bin at 

 interx al- in t 'u-re are breaks in its continuity. The 

 na-al -eptum i- pie-eir I'-shapcd structure, i he i op. ,| tin 1" 

 forminj it of the iloor of the region. Forming a roof over 

 the na-al nt--haped prenasal cartilage. Thi 

 broken at a -in;Jc place .-n one >ide to permit the e\it ot a b! 



vessel. The cartilagt does no( jx'rsist through the entire graft 

 but disappear- -hortU" be\ oiid the posterior end ot the na-al - 



The epidermi- of the head i- present in the .interior end of the 

 ft as an extensive, mon -s cornitied m..-- <-f ti--in- imbi-d- 



ded in me>ench\ me. A- it i- traced posteriorly it approai hesand 

 tinalK', at the p<>-teri<>r le\ el of the olfacto: 5, reaches the 



chorionii- surface "f the membrane where it i- unincorporated by 

 the ht. A -ingle lube-like growth of thi- epidermi- ha- come 

 to lie between the tip of the left olfactory sac and the forebrain. 



A- far as I have been able to di-c<.ver. the only data oil the 

 differentiation of the na-al epithelium when i-olated either com- 

 pletely or together with the immediate region, .ire furni-hed by 

 Lewis (PC-; ,; . This author record- two experiment- which 

 -how in the lii>t place that t he epithelium develop- indeitendently 



