144 Journ;il iit Entomology and Zoolog)' 



established. The fibrillae from one cell, in many cases, actually 

 mingle with the fibrillae within another cell. Non-medullated 

 fibers, it seems to me, probably afford means of transmission through 

 the sides of the fibers, as well as at the ends, although in many 

 cases the ends may be better adapted for the purpose. It may be 

 that the branchings at the ends of the processes of nerve cells are 

 for the purpose of furnishing a number of contacts which are better 

 than the sides of the fiber. 



2. I believe the structure of the nucleus, together with what we 

 know of nuclear composition and structure in general, precludes it 

 from any decided part in conduction. It seems merely a metabolic 

 center of less importance in mature nerve cells, as evidenced by 

 its loss of nuclear material. 



3. I believe fibrils are related both within and without cells in 

 a similar manner. That is, they run near, touch or cross to allow 

 the passage of impulses, but do not necessarily fuse. 



4. The chief fibrillar material of cell bodies and of areas 

 between cells, I believe, is about the same and is neuro-fibrillar or 

 conductive. A small portion of the cell-body is merely supportive 

 and neuroglia or other cells in the general fibrous mass of a ganglion 

 furnish varying amounts of supportive material between cells. 



5. Cells are related to each other grossly very often by neurites 

 and dentrites, but in many, if not all cases, fibrils, either in these and 

 formed from them, or free fibrils, relate cells, not so much as indi- 

 viduals as in groups. 



6. The impulse is carried in the fibrils. The stimulus in non- 

 medullated fibers is not so clearly separated as in meduUated. There 

 must be some latteral escape to other cells in ways as yet not under- 

 stood. Some insulation and definiteness in certain non-medullated 

 cells is accomplished by whole bundles for a single purpose pro- 

 tecting the central fibers from much lateral loss. Probably also 

 certain large clearly separated fibers because of their positions are 

 protected from lateral loss. 



7. I believe nerve cells do not act as individuals; their effect is 

 a massed one. Many cells supplying a region or a function act in 

 such a way that certain ceils or even areas might be lost out entirely 

 and yet the impulse be carried. 



