PLATE XII. 
Fig. 1. Section No. 7 of brain of embryo C. snrctus, earliest stage observed, passing 
through the upper and lower cerebral (embryonic) lobes (up. 1., low. 
(Do the upper cerebral lobes become (he calices and the lower cerebral lobes 
ultimately become the trabecule ?) (Sec lig. hue. I.), op. I., optic lobe; 
ant. 1., antenna! lobe; eye, outline of the eyes ; X &, Tollcs's objective, A eye- 
piece. 
Fig. la. Portion of the left upper cerebral lobe of fig. 1, magnified 400 diameters,] 
showing the gradual passage of the cortical ganglion cells iuto the central 
granular nervous substance, the granules (gran.) extending and filling up 
the spaces between the nucleated ganglion cells (gang, c); it will be noticed 
that there are at this time no nervous fibers. 
Fig. 2. Section No. f> of head of a more advanced embryo, just ready to hatch, the 
section not including any part of the brain, the cells represented being con- 
nective-tissue cells enveloping' the brain. The portions left blank in tigs. 
1, 7, and 9 are in the actual sections filled with similar connective-tissue 
(mesodermic) cells. 
Fig. 3. Section No. C of the same embryo, passing through the optic and antenna 
lobes. 
Fig. 4. Section No. 7 of the same, passing through the "upper cerebral lobes" oh 
calices of the future mushroom body (cer. /.), and also through the optic and 
antenna] lobes. 
Fig. 5. Section No. 8, passing through the brain (next behind No. 7). 
Fig. 0. Section No. 9, passing through what is probably (.') the mushroom body 
marked as the cerebral lobe (cer. 1.). 
Fig. 7. Section No. 10. The parts not well defined. 
Fig. 8. Section No. 11, through the brain of the same embryo as figs. 2-7, and passing 
through the upper and lower cerebral lobes, and the central body (cent, b.), at 
this point clearly indicated. Probably the " lower cerebral lobes " become 
the trabecular of the adult insect. The sections do not enable us to deter- 
mine with exactitude the history of the embryonic upper and lower cerebral 
lobes. (For enlarged views of the upper and lower cerebral lobes and the 
central body see Plate xiii, fig. 4) ; int. indicates the integument of the head. 
Fig. 9. Section No. 12 of the same embryo : up. 1., upper, low. 1., lower, cerebral lobes ;J 
<B8., oesophagus (compare also tigs. 6 and 7 of Plate xiii. representing sec- 
tions behind the head of the same embryo). 
Fig. 10. Section No. 6 of the younger embryo, passing in front of No. 7, fig. 1, of this' 
plate, and representing the subcesophageal ganglion, showing the form of 
the ganglion and the relation of the central granular nervous matter (gran.) 
to the envelope of cortical cells (gang, c.) ; Xl, Tolles's objective, B eye-piece. 
Figs. 2-9 were drawn with the same objective, A eye-piece. 
