Cambridge Philosophical Society. 487 



That whilst the edges of the furrow are closing, a -white line 

 having a filamentous appearance arises between it and each ganglion, 

 the connexion of which with the central parts corresponds with the 

 swellings which give to those parts a sinuous appearance. 



That another white line arises between the ganglia, and connects 

 them together, so as to cause them to offer collectively an arrange- 

 ment somewhat analogous to that which the ganglia of some inver- 

 tebrate animals present. 



That another line appears to proceed from each ganglion exter- 

 nally, and to join one which runs parallel with the axis of the body 

 and communicates with the cardiac ganglion. 



Resuming the pathological part of his subject, Professor Fisher 

 gave the following statement of the views he entertained on the 

 subject of Spina bifida, when that disease is situated in the lumbo- 

 sacral region* : — 



That the coalescence already described of the ganglia constitutes 

 the primary irregularity to which all the others that the disease pre- 

 sents may be directly or indirectly referred. 



That this coalescence is favoured by the position those ganglia 

 occupy, and by their volume, the comparative greatness of which 

 may be due to their connexion with the sacral plexus f. 



That the roots of the nerves appertaining to the united ganglia, 

 by virtue of their passing through the dura mater in one bundle, 

 become so irregularly connected with- the pia mater of the cord, as 

 to give rise to adhesions between that membrane and the arachnoid, 

 and between the latter and the dura mater. 



That this disordered condition of the pia mater has for its conse- 

 quence the anomalous position of the cord (which always adheres 

 to the inner surface of the posterior wall of the tumour), and even 

 in some instances a deficient development of that organ. 



That the beginning of the bifid state of the osseous canal corre- 

 sponds above to the point .where the cord becomes attached to the 

 posterior wall of the tumour J. 



pressed with the feeling, that since his results differed from those of other 

 embryologists, he might be mistaken about the nature of these bodies. He 

 finds, however, that they are confirmed in part by the observations of the 

 late Professor Rolando, and therefore .he has felt more confidence in com- 

 municating them. But whether the observations he has made, or the con- 

 clusions he has drawn from them, be correct or not, the development of 

 the spinal or intervertebral ganglia ought not to be lost sight of. 



* Although these views coincide with those the author communicated on 

 a previous occasion, and which were recorded in the London and Edin- 

 burgh Philosophical Magazine (vol. x. p. 316), still it may not be con- 

 sidered inappropriate if they be presented again, in association with the 

 additional matter he has brought forward. 



f The spinal ganglia are, at least about the middle of foetal life, richly 

 supplied with blood-vessels, which may also assist, along with the hyper- 

 trophy of the ganglia, in favouring their coalescence. 



% In all cases of Spina bifida, the defective formation of the osseous 

 canal corresponds with that of the cord ; where the latter assumes its 

 natural conformation, the canal becomes complete. 



