438 WILLIAM A. HILTON 



nectives. Many of the medial fibers may be traced out to the 

 optic lobes. Fibers from the largest median cephalic cells de- 

 scend the connectives. Fibers from cephalic and lateral cell 

 groups cross in the center of the brain and either run straight 

 into commissures or cross somewhat diagonally. Fibers from 

 the smaller cell groups on the connectives near antennal nerves 

 descend the connectives and ascend into the central parts of the 

 brain to the same side or the opposite side. The small cephalic 

 branches of the brain send fibers for a short distance into the 

 brain and cells near here supply them. The mass of the con- 

 nective fibers runs straight in to the central parts of the brain. 

 Fibers from cephalic lateral cells cross at angles to relate them- 

 selves to various cell groups, to run in the optic nerves and to 

 run into the central part of the brain. 



The connections of the optic ganglia were not studied. So far 

 as there is a special center in the brain to which all fibers con- 

 verge it would be the general region of median cephalic cells. 

 It is from this region that the larger cells probably send their 

 fibers long distances down the connectives to ventral ganglia. 



In general the distribution of tracts in the ventral ganglia is 

 as follows : 



1. Fibers in the connectives ascending or descending. 



2. Fibers from the branches or nerve trunks end, cross in 

 commissures and ascend or descend in the connectives. Many 

 end where they enter the ganglia or on the opposite side in the 

 same ganglion or in the opposite ganglion. 



3. Fibers in the commissures cross from cells of either group 

 and end in relation to cells of either group of the opposite gan- 

 glion. Fibers in the commissures may also be seen to ascend or 

 descend in the direction of the connectives. 



4. Each cell area of each ganglion is probably connected as 

 follows: a) Fibers to other cell areas of each side through the 

 commissures, b) Fibers to cell areas of each side not from the 

 other side through the commissures, c) Ascending fibers, d) 

 Descending fibers. 



The commissures are probably made up as follows: a) Fibers 

 from cells in upper levels, b) Fibers from lower levels, c) 



