344 



MANUAL OF HISTOLOGY. 



long piece has been cut out from a nervous trunk, connection is again 

 restored by means of new tissue. 



According to the early observations of Waller, which have been since con- 

 firmed by others, that part of the nerve situated at the distal side of the 

 cut degenerates down to its ultimate ramifications, with coagulation and 

 subsequent absorption, until eventually the neurilemma a]one remains, 

 which also disappears completely after a certain time, according to the 

 same investigator. Prom this we infer that a new formation of nervous 

 fibres must take place in order to effect connection with the central por- 

 tion. This last view is opposed by Lent, who asserts that a new filling-in 

 of medullary matter into the primitive sheath supervenes upon the union 

 of the two cut ends. According to Ujelt, finally the severed nerve fibres 

 only degenerate in pa/t completely, being replaced by neoplasis, whilst 

 other primitive tubes are capable of a regeneration subsequent to their 

 reunion. Lent, again, has observed a very interesting multiplication of 

 nuclei in the primitive sheath. But the whole question, as regards the 

 origin of the newly-formed interposed tissue, is worthy of being made the 

 subject of renewed research in the present state of histology. 



Whether regeneration of ganglion cells takes place is still uncertain. 

 Pathological new formation of nervous elements in other neoplasms is of 

 rare occurrence, as are also nervous tumours or neuromas. The latter may 

 consist of tubes or grey matter 



In atrophied nerves a decrease in the thickness of the primitive tubes 

 is manifest, and, instead of a continuous medulla, a number of fat globules 

 and granules are presented to us. 



16. Glandular-Tissue. 

 193. 



The definition of what we understand by a gland was, until compara- 

 tively recently, a matter of considerable difficulty, so that a talented 

 anatomist, more than thirty years ago, was fully justified in expressing 



...Of 



Fig. 325. Glands from the large 

 intestine of the rabbit. A fol- 

 licle filled with gland cells; 

 four others without cells, show- 

 ing the membrana propria. 



Fig. 326. A racemose so-called 

 mucous gland from the rab- 

 bit's ossophagus. a, the duct ; 

 6, the follicles; c, the invest- 

 ing connective tissue. 



himself thus: "That class of structures called glands is one of those 

 careless productions of an infant science, to define which, set it upon a 

 firm basis, and support it there, requires all the care and pains which the 

 latter can bestow in its present state of maturity." 



