Chapter 18 

 MAMMALS 



See also pages: 



6-22 structure of human eye 



26-8 refractive errors 



29-36, 247-53 human dioptrics, accom- 

 modation 



47 Fig. 21a 



49-50 horizontal cells, amacrines 



50-1 retinal nutrition 



51-2 optic nerve, chiasma 



56-60, 166, 176-7, 215-7 visual cells 



67 human retinal summation 



74-103, 168, 194, 198, 207, 211-2, 215-6, 

 245-6 vision 



81-103, 333-8, 462-72, 504-23 color vision 



104-17 embryology 



134-5, 138-9 relationships 



143, 191-6, 199-201, 203-5 yellow mtra- 

 ocular filters 



145, 164, 169, 170-1, 203-5, 208-9, 210 

 habits 



150, 166 photomechanical changes 



153-8, 162-3, 218-21, 227-8 pupil 



171-5 non-retinal acuity adaptations 



178-80, 367 blind spot 



181-3, 187-8, 190, 311-2 area centralis, 

 fovea 



210-4 non-retinal sensitivity adaptations 



213 tubular eyes 



228-35, 238-46 tapeta, eyeshine 



247-57, 283-8, 444-8 reraction, accommo- 

 dation 



285-6 ciliary body 



289-92, 296-300 visual fields 



300-3, 310-2 eye movements 



313-38, 341 stereopsis 



334-8 central visual pathways 



339 Fig. 124 



340 median eye 



342-65 movement perception 

 442-8 amphibious adaptations 

 523-4 dermal color changes 

 543-51 coloration of eye 



The Class Mammalia contains three major divisions which are not 

 serially related, but represent three branches from a single stem. The 

 lowest mammals, closest to the reptiles, are the monotremes. These egg- 

 laying forms include only the duck-bill or platypus (Ornithorhynchus) 

 and the echidnas or 'spiny ant-eaters' (Tachyglossus and ^aglossus 

 [= Echidna and Proechidna] ) . Ranking higher in point of specialization 

 and anatomical distinctness from the reptiles, but not derived directly 

 from monotremes like those now living, are the marsupials. These like- 

 wise have yolky eggs, but hatch them inside the body and bear the young 

 alive in an embryonic condition. The young complete their development 

 on a milk diet, outside the mother but usually inside an abdominal 

 pouch. In the common opossum, Didelphis virginictna, the 'embryology' 

 of the eye continues for 30-40 days after birth. The highest (placental) 

 mammals nourish their young inside the mother's body by means of a 

 'placenta'. They were not derived from marsupials, but with them, as 

 one of two branches. 



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