CEREBRAL HOMOLOGIES. 



43 



easily squeezed out wheu the brain is cut into. It is not 

 inclosed in hard parts, and is not defended from pressure or 

 injuries more than any other part." ('Physiological Cata- 

 logue,' 4to, vol. iii. p. 4, 1836.) 



Balfour* deems the nerve-cords in Feripatus and the pri- 

 mitive moUuscan type GJdton to be the circumoral ring longi- 

 tudinally extended. 



For the further development of this part of Compa- 

 rative Anatomy, I need only to refer to the rich series of 

 Monographs for which we are indebted to Mr. Robert 

 Garner, F.L.S., of Stoke-upon-Trentf, still in enjoyment 

 of health and intellectual vigour ; also to another, whose 

 loss we lament, the late Dr. Albany Hancock, F.R.S. % 



In his admirable researches on the Nervous System of 

 Insects, Newport § discovered that " the nervous cords between 

 the ganglia included two columns," and that "the inferior 

 column alone goes to the formation of the ganglia, whilst the 

 superior lies upon them without any perceptible enlargement." 

 Upon this he founded his distinction of the " motor " and 

 " sensitive " columns in Insects as in Vertebrates. This, of 

 itself, must weigh in the question of the homology of the 

 ganglionic cords of Articulates with the myelon of Verte- 

 brates ; and acceptors of such homology gain by a determi- 

 nation of the corresponding surfaces of the entire frame in 

 the two groups. If the ganglionic cord be the homologue of 



* 'Comparative Embrj'ology,' 8vo, 1881, vol. ii. p. 312. 



t See Ms beautifully illustrated memoirs in the Transactions of the 

 Linnean Society, vol. xvii. (1837), and in the Transactions of the Zoolo- 

 gical Society, vol. ii. (1835). 



■f. By monographs in the publications by the Ray Society, in the 

 ' Annals of Natural History,' and in the ' Philosophical Transactions,' with 

 his associate workers Embleton and Alder. 



§ ' Philosophical Transactions,' 1843, p. 243. 



