252 Journal of Comparative Neurology. 



paper by Parker (80) that the only change which has actually been ob- 

 served here is a trans(er or movement of the pigment granules zvithin 

 the cell, and no movement of the cell as a whole, such as Deyber as- 

 sumes. The probability is that this is what occurs also in the higher 

 forms. It will be recalled that this also was Angelucci's interpretation 

 of his own results. As to the changes in the rods and cones, this evi- 

 dence is good so far as it goes, and is certainly of more direct signifi- 

 cance than that from the wandering leucocyte, since the rods aud cones 

 are more stable and fixed and thus more comparable with the cortical 

 neurones. 



The other proof by analogy cited by Duval and Deyber, that 

 found in the olfactory epithelium cells, has been sufficiently met in 

 what was said with reference to other ciliated epithelium tissue. 



We pass now to the so-called direct proofs of the theory. These 

 are found in what is interpreted to be evidence of amoeboid movements 

 in the neurones themselves. A number of rearches by different inves- 

 tigors on pathological states and on the effects of fatigue on the neu- 

 rone are cited by Deyber and Duval as giving a histological basis for 

 the theory. Deyber refers to the older researches of Remak, Heiden- 

 hain, Ranvier, Nussbaum, Ogata, Platner, Nickolaides and Melenissos, 

 and of Eeke. But he takes up in detail only the researches of the past fif- 

 teen years which are also the more conclusive in his opinion. In 1884, 

 Flesch (34) in studying the Gasserian ganglion spoke of the migration of 

 the nucleus outside of the cell body. Magini (64) in 1890 spoke of the 

 displacement of a nucleolus in the motor nerve cells of the Torpedo 

 after strong excitation, the nucleolus becoming in such a case eccentric, 

 directed toward the axone, and enclosed by a heavy layer of karyo- 

 plasma. Vas (107) in studying the cervical sympathetic ganglion be- 

 fore and after excitation, showed, in 1892, that as a resultof the irritation 

 of the cell, the protoplasm became separated into two distinct zones, 

 an internal and an external. The nucleus also took an eccentric posi- 

 tion and the volume of the nucleus and of the whole cell underwent 

 changes. Lambert (54) in his researches on the cervical sympathetic 

 ganglion of the rabbit and young cat confirmed the results of Vas, ex- 

 cept with regard to the changes in the cell volume. Hodge during the 

 years 1889-1892 experimented on the spinal ganglion nerve cells of the 

 dog, cat and frog. He found (46 and 47) : A. For the nucleus : that 

 fatigue is accompanied (a) by a marked diminution in the volume of 

 the nucleus, (b) by a change from a smooth and rounded to a jagged 

 irregular outline, (c) by a loss of the open reticular appearance with a 

 darker stain ; B. For the cell protoplasm: that fatigue is accompanied. 



