248 Annals Entomological Society of America [Vol. IV, 



SMALL GANGLIA OF THE HEAD. 



Connected with the arched nerves somewhat cephalad of the 

 brain is the frontal ganglion. This in well stained preparations 

 may be seen to have a central deep staining mass surrounded 

 by nerve cells, the processes of some of which run into the 

 central mass, while those of others run out from the cell, and 

 down into the nerve which runs under the brain and connects 

 this with the smaller so-called vagus ganglion. This last is 

 like the former only smaller and fewer cells surround the central 

 mass, some of the fibers run from this and probably also rather 

 directly from the cells of the ganglion, down and out the two 

 caudal branches. Occasionally the two lateral ganglia of the 

 esophagus take the stain but their connections or structure was 

 not especially studied. They seemed to differ from the other 

 two ganglia, as they showed from the surface no nerve cells, the 

 whole body taking on a uniform deep blue color. Sections 

 showed them composed of very many cells closely massed 

 together. 



Sections of the frontal ganglion show a small mass of cells 

 quite well filling the caudal end, a few larger, but mostly 

 smaller cells of the same general sort found in other places. 

 Of these there were about two large and eight smaller ones at a 

 level where the ventral nerves come off on each side of the 

 "Punktsubstanz," although farther cephalad than the place 

 where these nerves are seen from the surface. Farther cephalad 

 where there are only three or four large cells, fibers cross in 

 various directions in the central portion of the ganglion. A 

 large cell for instance was seen to send a process into the center 

 of the ganglion where it broke up into a number of branches. 

 Fibers cross in the various directions but most run longitudi- 

 nally. At a level where a branch to the frontal ganglion arises, 

 there are no nerve cells, the central part of the ganglion is 

 divided into three masses of longitudinal fibers by trachea and 

 cross fibers. This division is continued only for a short 

 distance. 



Farther along a dorsal and a few small ventral cells come in. 

 The central mass of fibers is rather uniform, but made up of 

 both cross and longitudinal strands. A little farther cephalad 

 three cells come in dorsally at about the level where the arched 

 nerves come off. Fibers running from side to side connect 



