CONTENTS. Xlll 



PAGE 

 in; reactions to stimuli, 112; structure, 113; the flabellum, 113; the branchial 



warts, 115; the slime buds, 116; the auditory organ, 120; lateral line organs of 

 vertebrates; summary, 121. 



CHAPTER VIII. 



LARVAL OCELLI AND THE PARIETAL EYE . 125-148 



I. The different kinds of eyes in arthropods and vertebrates, 125; eyes of orthro- 

 pods, 125; larval ocelli, 125; frontal ocelli or stemmata, 125; parietal eye, lateral 

 eyes, cerebral eyes of vertebrates, 126; parietal eye, lateral eye, olfactory organ, 

 127. II. The eyes as segmental sense organs, 127; procephalic and thoracic sense 

 organs. III. The larval ocelli of insects, 128; larval ocelli, stemmata. IV. The 

 parietal eye, 129; the parietal eye of the scorpion, 129; the parietal eye of limulus, 

 131; development; palial fold; epiphysis; anterior neuropore; change of position; 

 endoparietal and ectoparietal eye; nerves; retinal cells; the parietal eye of bran- 

 chipus, 136; the parietal eye of apus, 138; the parietal eye of vertebrates, 139; 

 petromyzon, 140; parietal eye vesicle, 140; ganglia, 142; asymmetry; comparison 

 with arthropods; the lenses of the parietal eye, 144; location of the placodes, 146; 

 minute structure, 140; summary, 147. 



CHAPTER IX. 



THE COMPOUND EYES OF ARTHROPODS AND THE LATERAL EYES OF VERTEBRATES . 149-159 

 I. Compound eyes of arthropods, 149; A. serial location, 149; B. development, 

 150. II. Lateral eyes of vertebrates, 151; location, 151; origin of the chroid fis- 

 sure and the blind spot, 151; the retinal-cell pattern, 153; the retinal ganglion, 153; 

 the lens, 153; origin of the imperfections of the vertebrate eye, 154. III. The 

 optic ganglia, 154; location, 154; parietal eye ganglia, 155; lateral eye ganglia, 

 optic lobes, 155; minute structure in limulus, 155. IV. Comparison with verte- 

 brates, 157; summary and conclusion, 158. 



CHAPTER X. 



THE OLFACTORY ORGANS OF ARTHROPODS AND VERTEBRATES . 160-173 



I. The olfactory organ of limulus, 160; structure in adult, 160; gross structure; 

 minute structure; development of olfactory organ and nerves, 162; olfactory 

 placodes; lateral olfactory nerves; median olfactory nerve; summary, 163. II. 

 The olfactory lobes of arachnids, 164; development; scorpion and spiders; limulus; 

 development; structure. III. The olfactory organs in phyllopods, frontal organs, 

 p. 165; branchipus, p. 166; apus, 167. IV. Comparison of olfactory organs of 

 vertebrates and arthropods, 168; i. number of placodes, 168; 2. number of nerves, 

 169; 3. structure and termination of the nerves, 169; 4. origin of the olfactory 

 ganglia, 170; 5. position of placode cells, 170; 6. serial location of the placodes and 

 their migration, 170; 7. olfactory lobes, 171; 8. function, 171; summary and con- 

 clusion, 172. 



CHAPTER XL 



FUNCTIONS OF THE BRAIN . . . . 174-194 



Parti. Introduction, methods, 175; description of experiments, 176-186. Part 



II. Summary of experimental and anatomical results, gustatory reflexes, structure 

 of gustatory apparatus, 186; the nerve-muscle chewing apparatus, 188; experi- 



