SECT. 31.] 



NERVOUS TISSUE. 



69 



middle sized, 0'002'" to 0*004" 

 They are either isolated 



course, the fibres running 



to 0"002 

 to O'OI 

 iii their 



from the centre to the periphery, 

 or they divide, especially in their 

 terminal distribution, into a larger 

 or smaller number of branches ; or, 

 lastly, they form true anastomoses 

 and networks. All nerve-fibres are 

 connected with nerve-cells; either 

 arising from them, or being inter- 

 rupted in their course by interpolated 

 ganglionic cells. These nerve-cells, 

 or, as they are called in the ganglia, 

 ganglionic cells, ganglionic globules, 

 have the ordinary characters of cells. 

 Their membrane presents nothing- 

 Fig. 23. 



and thick, 0004" 



Fig. 27. 



Ganglionic globule from the pike (bipolar), 

 running nut at the two extremities into dark-bor- 

 dered nerve-tubes; treated with arsenious acid, 

 and magnified 350 times, a. Envelope of the 

 globule; b. Sheath ot the nerve; c. medulla of 

 the nerve; d. axial- fibre connected with the con- 

 tents c. of the ganglionic globule retracted from 

 the envelope. 



Unman nerve-tubes ; magnified 350 times. 

 Three fine, one of which is varicose; one 

 middling thick, and simply contoured ; and 

 three thick, two of which are double contoured, 

 and one with granular contents. 



peculiar, except that it is fre- 

 quently very delicate, or even, as 

 in the large central masses, per- 

 haps entirely disappears. The 

 contents are finely granular and 

 pulpy, very frequently with pig- 

 ment, and invariably include a 

 beautiful vesicular nucleus with 

 a large nucleolus. In size, the 

 nerve-cells vary from o - oo3'" 

 to 0*04'" ; and with respect 

 to their form, they are chiefly 

 distinguished into round, fusi- 

 form, and stellate. The two 

 latter kinds consist of nerve-cells 

 running out into two, three, or 

 as many as eight and more pro- 

 cesses, which, in some cases, pass, 

 after a short course, into medul- 

 lated nerve-tubes, in others, pre- 

 sent a greater independence, 



