90 THE NERVOUS SYSTEM OF THE FROG. 
v. The cornua: anterior or ventral, and posterior or 
dorsal, into which the grey matter is produced 
on either side. 
vi. The central canal of the cord: in the median line, 
nearer the ventral than the dorsal surface. - 
vii. The nerve roots; only seen if the section happens 
to pass through their points of origin. 
a. The posterior or dorsal root; connected with 
the posterior cornu of the grey matter: a 
single thick band of nerve fibres. 
(. The anterior or ventral root; connected with 
the anterior cornu of the grey matter: a 
number of very slender bands of nerve fibres. 
b. With high power. 
i. The ganglion cells; large nucleated branched cells 
lying in groups in the grey matter: largest and 
most numerous in the anterior cornua. 
i. The neuroglia: a delicate network of connective 
tissue fibres and cells penetrating and supporting 
all parts of the cord, and continuous at the sur- 
face with the pia mater. 
ii. The pia mater: the delicate connective tissue 
membrane ensheathing the cord and extending 
into the fissures. 
iv. The bloodvessels of the cord: small and numerous : 
enter from the pia mater. 
The ciliated epithelium lining the central canal. 
baie 
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