STEKVOUS TISSUE. 



108 



however, affirmed, as the result of his examination, that the matter 

 which fills the tubes is of an oily nature, differing, in no essential 

 respect, from butter or soft fat, and remaining of a fluid consistence 

 during the life of the 



animal, or whilst it re- Fi - 26 - 



tains its natural tem- 

 perature; but becoming 

 granular or solid when 

 the animal dies. The 

 diameter of these cylin- 

 drical tubuli has been 

 estimated to vary from 

 about the yjpth to the 

 2 Jo ta of a line. The 

 nerves are wholly com- 

 posed of it. 



The tubular nervous 

 matter, wherever it is 

 found, seems to consist 

 of fibres, which have a 

 definite arrangement. 

 Two kinds of primitive 

 fibre, according to the 

 researches of Messrs. 

 Todd and Bowman, 1 are 

 present in the nervous 

 system, which they dis- 

 tinguish as the tubular 



-fihr? nr nerve tiihe f\r\<\ or primitive band. 



J w c. Figure (imaginary) intended to represent the appearances oc- 



the CielatinOUS fibre casionally seen in the tubular fibres. 1, 1. Membrane of the tube 



, JP r i r_ seen at P af ts where the white substance has separated from it. 2. 



the lOrmer infinitely the A part where the white substance is interrupted. 3. Axi 



i ,1 ing beyond the broken end of the tube. 4. Part of the c< 



more numerous, and the the tube escaped. 

 latter found chiefly in 

 the sympathetic system- The tubular 

 fibres vary in diameter from y^ ^th even 



to TTJ J o o tn f an i ncn 5 but tne i r average 

 width is from ^^tnto ^^th of an inch. 

 The gelatinous fibre is devoid of the 

 whiteness that characterizes the tubular 

 fibre ; and the gray colour of certain 

 nerves, it has been thought, is dependent 

 chiefly upon the presence of a large 

 proportion of gelatinous fibres. Hence 

 they have been sometimes termed gray 

 fibres. These are in general smaller 

 than the tubular fibres, their dia- 

 meter ranging between the g^^th and 

 tne 4 o'o oth f an 



Tubular Nerve-fibres. 



A. Tubular nerve-fibres, showing the sinuous outline and double 

 contours. 



B. Diagram to show the parts of a tubular fibre, viz. : 1, 1. Mem- 

 branous tube. 2,2. White substance or medullary sheath. 3. Axis 



s project- 

 contents of 



Fig. 27. 



C 5 



Gelatinous Nerve-fibres. 



(a and b magnified 340 diameters, after 

 Hannover ; c and a after Remak.) 



1 Dr. Todd, Art. Nervous Centres, in Cyclop, of Anat. and Phys., Pt. xxvi., p. 707 ; and 

 The Physiological Anatomy and Physiology of Man, p. 208, London, 1845. 



