322 



MANUAL OF HISTOLOGY. 



brates (fig. 310), that the dark-edged primitive fibre (a, b) approaches the 

 muscle fibre (g, left), enclosed within a loose nucleated sheath (c, d), and 

 pierces the sarkolemma, while the neurilemma becomes continuous with 

 the latter (e, left). Beneath the sheath of the muscle the terminal 

 filament swells up into a finely granular mass of a flattened form containing 

 nuclei (/, left). This merges at its edges (e, e}, and concave under 

 surface, into the fleshy substance of the fibre (4). 



To this structure in which the fibre ends, and which occurs only singly 

 in mammalian muscle fibres, has been given the very appropriate name 



of " terminal plate " by 

 Krause, Rouget, Engelmann, 

 and others ; while Kuhne 

 calls it the "neural emin- 

 ence " (NervenliugeT). 



In the mammalian body, 

 in which these terminal 

 plates are well developed, 

 and occupy a not incon- 

 siderable portion of the sur- 

 face of the muscle fibre, 

 their diameter ranges from 

 0-0399 to 0-0602 mm., while 

 in thickness they vary. 



Their nuclei are smooth, 

 clear, oval, and contain one 

 or two nucleoli, thereby dif- 

 fering from the more opaque 

 formations of the neuri- 

 lemma, and likewise from 

 those of the muscular fibres. 

 In diameter they range from 

 0-0049 to 0-0099 mm. 

 Their number is liable to 

 variation ; from four to 

 twenty being found in one 

 plate. 



Terminal plates of the same kind are to be met with in birds and 

 reptiles. 



But a number of questions relative to the nature of these neural 

 eminences must for the present be left unanswered, and perhaps for a 

 long time still ; for instance : Do we see in them the whole of the ultimate 

 distribution of the fibre? Does the finely granular substance of which 

 they are composed take its origin from a transformation of the axis 

 cylinder, or does the latter end within them, and, if so, in what form 1 ? On 

 these points there is no lack of variety of opinion. 



According to Jfrause, we may recognise a pale, single, double, or triple 

 fibre (axis cylinder) within the terminal plate, ending with a swelling or 

 knob upon it. A very fine and somewhat tortuous fibre was also 

 remarked in the same situation by Sclwnn. But from Killings researches, 

 which from our own observations we are inclined to regard as correct, we 

 learn that the structure is far more complicated. On its entrance into 

 the^ terminal apparatus (fig. 311), the axis cylinder of the nerve fibre 

 divides, and spreads out with further ramification into a peculiar pale 



Fig. 310. Two muscular fibres from tlie psoas of the Guinea 

 pig, showing terminations of nerves, a, 6, the primitive 

 fibres with their transition into the terminal plates e,/; c, 

 neurilemma with nuclei d, d, continuous with the sarko- 

 lemma g, g\ A, muscle nuclei. 



