216 JOURNAX, OF ENTOMOLOGY AND ZOOLOGY 



4. The optic lobe and brain area become better and better 

 marked. On each side of the middle Ime there are three chief areas 

 developed. 



5. Ganglia make themselves evident for each of the appendages 

 of the head region below the eyes. There is a crowding together 

 in this region and fusion of the ganglia. The first and second anten- 

 nae have their ganglia soon fused with the supra-oesophageal mass. 

 There is in adciition to these and the ocular masses an extra gan- 

 glionic area which fi^ses also, but no appendage is evident in con- 

 nection with it. There are also other centers in the cerebral mass 

 which may simply be centers of cell growth, as indeed this little 

 ganglion may be. 



6. The lateral ganglia of the other head appendages fuse into 

 the suboesophageal mass. 



7. The ganglia of the body are gradually added to from the 

 teloblastic region at the caudal end of the body. At first the body 

 ganglia are only slightly marked off from the surrounding ecto- 

 derm. These early formed ganglia are much alike in early stages, 

 and each has its appendage. At a time of a maximum number of 

 bociy segments, such as stages a little later than Fig. 8, there is no 

 difference in the ganglia at different segments, except that the more 

 caudal ones are a little smaller and less evident. 



8. At an early period the ganglia of all appendages are made up 

 of at least two lateral parts. Some of the ganglia in the thoracic 

 region seem also to be made up of two parts each on each sicie. 



9. When the ganglia are first formed there is little demarcation 

 between them and they are not separate from the skin ectoderm. 

 Later the skin ectoderm forms a distinct layer on the ventral side, 

 as shown in Figs. 33 and 34. 



10. In the bociy ganglia the nerve fibres begin to make them- 

 selves evident on the dorsal side as shown in Figs. 48 and 49. 



11. In the brain, the fibers from the cells are first evident in 

 central areas, as in Fig. 47. 



12. The ganglia of the abdominal region become fuseci into one 

 mass when the young are from 3 to 3^2 mm. in length, as shown 

 in Fig. 46. 



