346 Zentralblatt für Physiologie. Xr. H 



of the spinal cord. The probability is that the fat g-lobules common- 

 ly present in the nerve roots were mistal^en by Michailow for 

 degenerating nerve fibres, and that injuries in the removal of the 

 spinal cord frora the body caused an appearance of degeneration 

 in the spinal tracts. However this may be, no conclusion can be 

 drawn from Michailow's experiments as to the course of the sym- 

 pathetic nerve fibres. 



The course of the synipathetic fibres as described by myself 

 has been based partly upon physiological experiments, and partly 

 upon histological observations on the fibres which degenerate after 

 nerve section. The results obtained by the two methods agvee. Part 

 of the experiments consisted in stimulating before and after the 

 use ,of nicotine. Michailow states that I have pointed out the 

 „Launenhaftigkeit und Unbeständigkeit" of the nicotine method. 

 This is not the case. What I have done is to point out the con- 

 ditions in which trustworthy conclusions can be drawn. Michailow 

 considers that because nicotine has a different degree of stimulating 

 and paralysing action in different animals, and on the different 

 autonomic ganglia of the same animal, no deduction can be drawn 

 from the effects of nicotine. This is a very singular conclusion. On 

 the same method of argument, it would follow that because curare 

 paralyses the nerves supplying the different striated muscles of ver- 

 tebrates with different degrees of ease, and does not paralyse the 

 striated muscles of invertebrates, no deduction can be drawn from 

 the effects of curare. 



In the observations on the degeneration of sympathetic nerves 

 made by myself, and by Anderson and myself the nerves were 

 treated with osmic acid and teased out in dilute glycerine^), 

 Michailow states that this method is imperfect and that making 

 sections of nerves treated by a modified Marchi method is a better 

 one-). This also is not the case. By the method used by Michai- 

 low, the fat globules of a degenerated fibre cannot be distinguished 

 from fat globules which do not arise from a nerve fibre; the 

 number of degenerated fibres cannot be determined, since the sec- 

 tion may pass through a portion of the nerve from which the myelin 

 has been absorbed; the size of the degenerated fibres cannot be 

 determined since they are moniliform; and lastly the sound modul- 

 lated fibres cannot be countod. The teasing method has none of 

 these drawbacks, and Michailow's befief that degenerated nerve 

 fibres after treatment with osmic acid are too fragile to be teased 

 is a pure Illusion. 



1) Michailow is mi.staken in supposing that we sometimes placed 

 the nerves in alcohol l)cfore i)lacing theni in osmic acid. He is also, I may 

 mention, mistaken in saying that I describe the first seven thoracic nerves 

 as having dilator libres for the pupil, I describe the first three only as 

 having such (Ihres. 



2) Trusclikowsky is quoted by Michailow with approval since he 

 used the Marchi method. He faiis however to point out that when Trusch- 

 kowsky performed the same Operation as hiniself, the result was different. 



