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TABLE XXXIX. 



Systematic Survey of the Sequence, according to Age, of the Human 

 Organ-systems. 

 (Phylogenetic Classification of Vertebrate Organs.) 

 (On the right are given the Ancestral Stages, in which the respective 

 organs probably first appeared.) 



1. Fibst Stage in the Evolution op Organs. 



I. Skin and Intestinal Systems. 



The two Systems appear first, and simultaneously, in the Gastread ancestors. 



A 1. Simple exoderm Gastraeads 



A 2. Outer skin (Skin-sensory layer) and > w „ rTria 

 leather skin (Skin-fibrous layer) J ™ 0Tma 

 A 3. Outer skin, with hairs, glands, etc. Mammals 



B 1. Simple entoderm Gastraads 



B 2. Intestinal epithelium (Intestinal-glan- \ 



dular layer) and intestinal muscular [ Worms 

 6kin (Intestinal-fibrous layer) ) 



B 3. Gill-intestine and stomach-intestine Chorda-animals 



I. A. Skin-system 



(Systema dermale) 



I. B. Intestinal system 



(Systema gastrale) 



2. Second Stage in the Evolution op Organs. 

 II. Nerve and Muscle Systems. 

 The two Systems appear first, and simultaneously, in the Primitive Worm ancestors. 



Primitive Worms 



Chorda-animals 



Monorhina 



Primitive Worms 



Acrania 



Fishes 



II. C. Nerve-system 



(Systema nerveum) 



II. D. Muscle-system 



(Systema muscalare) 



iCl. Upper throat ganglia 

 j C 2. Simple medullary tube 

 ( C 3. Brain and spinal marrow 

 D 1. Skin-muscle pouch 

 D 2. Side muscles of the trunk 

 D 3. Trunk and limb muscles 



& Third Stage in the Evolution op Organs. 



III. Kidney and Vascular Systems. 



The two Systems first appear, one after the other, in the Soft-worm ancestors (Scolecida). 



El. Primitive kidney canals Scolecida 



E 2. Segmental canals Acrania ? 



E3. Primitive kidneys Monorhina 



E4. Permanent kidneys Protamnia 



F 1. Simple coelom Scolecida 



F 2. Dorsal and ventral vessels Worms 



F3. Heart (part of the ventral vessel) Chorda-animals 



Fi. Heart, with auricle and ventricle Monorhina 



III. E. Kidney-system 

 (Systema renale) 



m.F. Vascular system 



(Systema vasculare) 



4. Fourth Stage in the Evolution op Organs. 

 IV. Skeleton and Sexual Systems. 

 The two Systems first appear, one after the other, in the Chordonia-ancestors. 



rGl. Simple notochord 

 ) G2. Cartilaginous primitive skull 

 *j (? 3. Gill-arches, ribs, limbs 

 \G 4. Limbs, with five digits 

 rH\. Simple hermaphrodite glands 

 ) HI. Distinct testes and ovaries 

 J 2? 3. Seed-duct and oviduct 

 I Hi. Phallus (penis, clitoris) 



IV. O. Skeleton-system 



(Systema skeletare) 



IV. H. Sexual system 



(Systema sexuale) 



Chorda-animals 



Monorhina 



Selachii 



Amphibia 



Chorda-ar 



Acrania 



Selachii 



Protamnia 



57 



