26 



FATTY DEGEXEEATION 



Fig. 8. 



the nerve-medulla described in § 16 ouglit to be regarded as the 

 first step in the dissociation of an amalgam of albuminoid and 

 fatty matter. For, by the common consent of all those authors 

 who have occupied themselves with this subject, the subsequent 

 changes are only a continuation, or, in other words, a carrying 

 out of that still enigmatical phenomenon. 



The large dark-bordered drops of my- 

 elin break up in the course of from two to 

 four weeks into globules of progressively 

 smaller size, which can no longer be 

 distinguished from oil globules, either 

 by their microscopical or their micro- 

 chemical characters. Side by side with 

 them minute protein molecules of a paler 

 tint make their appearance ; a fatty and 

 granular detritus results, which remains 

 enclosed for a time in the tubes of 

 neurilemma, and is ultimately absorbed. 

 The axis cylinder remains intact for 

 about six weeks in the disintegrating 

 medullary sheath. If at any time 

 during this period the connexion of the 

 peripheral portion with the central 

 stump is re-established, the sheath fills 

 again with meduhary matter, and the 

 axis cylinder resumes its interrupted 

 functions ; in the contrary event it 

 becomes granular and splits up, even 

 before the absorption of the oily dehris is quite accomplished. 

 The empty neurilemma now collapses into longitudinal folds, 

 exhibiting here and there an elongated mass of fat granules, in 

 the interior of which a nucleus may be demonstrated with 

 carmine. 



§ 33. The fatty granular metamorphosis, or caseation of cells, 

 may conveniently be regarded as a variety of fatty degeneration. 

 The latter term is that chosen by VircJiow ; it is based upon a 

 close resemblance between the yellowish white, dense, homo- 

 geneous, rotten, or greasy mass, which is the final product of 

 this metamorphosis and certain sorts of cheese. 



It used formerly to be thought that the substance in question 



Fatty degeneration of 

 double-bordered nerve 

 fibres in the periplieral 

 part of a divided cere- 

 l)ro-spinal nerve. a. 

 After three days have 

 elapsed; h. After a 

 fortnight ; c. After 

 three weeks ; d. After 

 two months, ■^^. 



