1911] Nervous System of Corydalis 249 



these nerves through the center of the ganglion. 



The so-called vagus ganglion has a central mass of fibers and 

 at its central part a nearly double row of cells closely packed 

 about this central fibrous mass, these cells are continued down 

 from the center a short distance, especially on the dorsal side. 



THE BRAIN STUDIED IN SECTION. 



(Plate XVI, Figs. 1-4.) 



Only the main features of the structure of this complicated 

 organ will be given at this time. Many of the elements of the 

 brain of the adult may be present in the larva but for the 

 proper interpretation of these it will be necessary to follow up 

 this work with studies on the ganglia of pupae and adults. 



As in the other centers, a central fibrous mass forms the 

 bulk of the organ and about this central " Punktsubstanz " 

 nerve cells are grouped in great numbers on practically all sides 

 but the ventral. As in the other ganglia, large and small nerve 

 cells and small neuroblasts are found, the latter are especially 

 abundant and occur in great masses. Besides these, filling in 

 between and in places where there are no nerve cells is the 

 neuroglia network, which is often continued to the layer of sur- 

 face supporting cells just under the chitinous sheath of the 

 ganglion. 



In sections we may recognize the dense staining parts seen in 

 surface views to be masses of fibers more or less complexly 

 arranged in the central and ventral portion, more or less par- 

 alleled by straight bands of the entering nerve trunks. Some 

 of the special denser masses of fibers have already been described 

 from surface views as that in the ocular lobe just as it joins the 

 brain and in from the little spherical area just within and 

 beyond this point. These two masses although quite separate 

 from each other dorsally, ventrally and laterally are centrally 

 connected by fibers and are also connected to each other to a 

 less degree in the same way. The central fibers described in 

 connection with the crura cerebri, are continued down into the 

 labral lobe, but the deepest mass is in the central portion 

 dorsally where it is somewhat lobed because of groups of cells 

 on the surface and due to the processes of some of these cells 

 passing down into the center. In this central "Punktsub- 

 stanz" either side of the middle line, is a well marked denser 

 group of fibers, a rod of substance projecting from those on the 



