TISSUES OF THE BODY. 



311 



177. 



We now turn to the cellular elements or the ganglion corpuscles, whose 

 appearance is very characteristic, with the exception of many in the brain 

 and spinal cord, where their boundaries are difficult to define. They 

 may be divided into those without processes (fig. 302) and those with 

 processes (fig. 303). To the first-mentioned species the term " apolar " 

 has been applied, and to the latter " unipolar," " bipolar," or " multipolar," 

 according to the number of their ramifications. 



In every variety of size, from 0*0992 mm. down to 0-0451-0-0226- 

 0-0018 mm. and even less, we meet with these cellular bodies of spherical, 

 oval, pear-shaped, or renal form. In these are situated spheroidal vesicular 

 nuclei of 0'0180-0'1090 mm., with a round slightly lustrous nucleolus of 

 0'0029-0'0045 mm. Another round point, frequently visible in the 

 interior of the latter either granular or clear has been given by 

 Mauthner the name of nucleolulus (fig. 308). Not unfrequently the 

 nucleolus is double, but the nucleus is seldom so. The latter, unlike 

 most nuclear formations, gives way comparatively rapidly to the action of 

 concentrated acetic acid. 



The contents of these cells, probably a species of protoplasm, appears 

 as a tough doughy mass, with numerous minute granules of a protein 

 substance, and in addition to these, fat molecules, soluble in alcohol and 



Fig. 302. Ganglion cells from a mammal. A, Cells Fig 303. Multipolar ganglion 

 with connective-tissue envelope, from which Re- cells with protoplasm pro- 

 raaA's tibres take origin, d, d; a, anon-nucleated cesses, from the grey sub- 

 cell ; 6, two cells with single nuclei; and c, one stance of the human brain 

 with two of the latter structures. B, A ganglion 

 cell destitute of envelope. 



ether, and, not at all unfrequently, particles of yellow, brown (fig. 303). 

 or black pigment (fig. 305, 4). The latter substances offer a most 

 determined resistance to the action of alkalies. 



All these ganglion cells, the central as well as the peripheral, are 

 destitute of distinct membranes. In the grey matter of the nervous 

 centres they are imbedded in that fibrillated sustentacular substance 

 already mentioned at p. 197. In the peripheral ganglia, on the other 

 hand, of man and the vertebrates, they are usually enclosed in envelopes 

 21 



