mi 



in front [nd, whnva> in tho | 



illy. n.-ar tin- origin of tin- ira ! . " nrurul 



fund.-, in- still 'iinected with 



i.-r. TiM- o.nnrctioii app ars to be 

 most conspicuously develop* d ami most p.-r- 



'lit in tin- ( 



ha> 1- M railed the longitudinal con 

 sure l'\ i le the ganglia are 



found th primitive segments (mp,mp'), each 

 of which at this tim- .-till .. \hil.its within 

 narrow iiure. 



In a monographic rij.heral ^Hi^B-~ *P* 



from the preceding 



account, in \\hich UALFOL-K, KH.I.IKI:I{, KABL, 



HI-:NSI:N. SACKMKIIL, KAMSC HI:NKO, and <; 



agree. lie- helieves th.it tin- fundaments of the 



ganglia arise, not out of tin- neural tube, hut out 



the deeper cell-layers ,f the adjacent part of 



Ho finds that tln-y are from 



tin- beginning separated from each other and eg- 

 mentally arranged. According to him, mor 

 they inakr their appeara: . ^tated 



in the preceding account; for they are already 

 recognisable as especially t!n< 

 outer germ-layer at the light and left of the neural 

 plate when ; first begins to bo h^nt inward. 



iy. upon the closure <.f the u, unil I p come 



to lie ::e raphe and the primitive ep i here they grow 



down ventrally at the >ides of the brain and spinal 



BEARD approximates in his results the conception lirst expressed and 



quently maintained hy His. For I! Lranglionic ridge, not 



from the raphe of the neural tul>e, hut from a ng part of the 



outer germ-layer, which he names intermediate cord (Xwi-M-lienstram,- 



accuracy of Bi: ription i-. 1U.BL and 



litl'. ivnt vii-\\- an- : iiiniT the changes 



Nvhich take place in tin- hiii'lam* nts of tin- spinal iMiiirlia: 



According to His :nnl SA;K.MI:III. th separate ganglion: 

 ments are comp'r'.' ly letaclird' from ihc neural tul^e, and for a timo 

 lie at th. 1 it without an\ 'ii with it whai 



Secondarily a union is a^ain f>talli>lu'd. throu^li the development 

 of the dor.-al nt'r\c roots, by the formation of nervr-lilirilhe. which 

 oitli r urow out from the spinal cord into the ganglion, or from tin- 

 ganglion into the >pinal cord, or in both direction- IIUIL 



Fig. M9.-Fronul section of 

 a Lizard embryo, after 

 SAOKV 



. neural 



HWMBWtod ::it- ;- -p::.. i! 



gauglia; mj/, the part of 



produce* the muscle-plate ; 

 m/i, outer lajer 



