148 Journal of Comparative Neurology. 



XXII, which represents the best specimen of motor cell that 

 my preparations offered. That it is motor in nature is assumed 

 from its general appearance, resembling to a certain extent the 

 motor fibers described and figured by Bethe ( 95), and the fact 

 that it is cut off near the cut end of a large fiber not figured 

 that passes into the antenno-motor nerve and with which it ap- 

 pears to have been continuous, but on account of a slight 

 bend outside the plane of the razor was cut in two. This ap- 

 peared in a nearly sagittal section. In a thick section cut in the 

 frontal plane, or nearly transversely to the main axis of the 

 animal's body, fibers were seen, siich as one represented in 

 Plates XVII and XX, sending a process into a tract of fibers 

 that appeared to pass down behind the antennal lobe, apparently 

 into the root of the antennal nerve, which were therefore thought 

 to be motor fibers. Combining these two with what was seen 

 of fibers in other sections in about the same locality as the 

 motor cell mentioned it would appear that the large motor cells 

 send a process into the fibrillar substance, which almost imme- 

 diately gives off small branches that may end at a considerable 

 distance from their point of origin. The process becomes very 

 much enlarged for a considerable extent of its course and may 

 even send off branches of considerable size before passing on 

 into the root of a nerve as a small fiber. 



5. The commissural fibers, which are doubtless of the gen- 

 eral T-shaped form, though I have not been able to find their 

 cells of origin. They pass from one side of the brain to the 

 other and may be represented by the fibers composing the 

 superior commissure. The fibers composing the so-called com- 

 missure of the optic lobes may possibly also be classed here. 

 Other fibers there are in plenty than those gathered into tracts 

 passing between the two halves of the brain, but they are better 

 classed with the next group. 



6. Association fibers seemingly serving the purpose of con- 

 necting the elemejits already described with one another. These 

 are mostly large profusely and irregularly branching forms 

 some of which are shown in plate XXII. In some^cases I have 

 been able to make out the cells of these, in others I have not. 



