( 367 ) 

 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. First Stage in the Evolution of Organs. 



I. Skin and Intestinal Systems. 



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



/ A 1. Simple exoderm Gastraeads 



I. A. Skin-system \ A 2. Outer skin (Skin-sensory layer) and ^ Worms 



{Systema dermale) \ leather skin (Skin-fibrous layer) j 



\ A3. Outer skin, with hairs, glands, etc. Mammals 



/ B 1. Simple entoderm GiAStiaeads 



T 7? TntPstiml svslrm I £ 2. Iirtestinal epithelium (Intestinal-glan- ) 



i. B. intestinal system i dular layer) and intestinal muscular J Worms 



^ystema gast) cut) l skin (Intestinal-fibrous layer) ) 



\B3. Gill-intestine and stomach-intestine Chorda-animals 



2. Second Stage in the Evolution of Organs. 



II. Nerve and Muscle Systems. 



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

 TT r Npwp *v*iPm / C 1. Upper throat ganglia Primitive Worms 



(''vstllaTrveum-) C 2 ' £ im P le medulla T tu ^ Chorda-animals 



^ystema net veum) { c 3 Brain and gpinal marrow Monorhina 



TT n Mnsele-svstem ( D L Skin - musc le pouch Primitive Worms 



3. Third Stage in the Evolution of Organs. 



III. Kidney and Vascular Systems. 



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



I El. Primitive kidney canals Scolecida 



El. Segmental canals Acrania? 



E3. Primitive kidneys Monorhina 



J? 4. Permanent kidneys Protamnia 



rFl. Simple ccelom Seolecida 



III. F. Vascular system ) F 2. Dorsal and ventral vessels Worms 



(Systema vasculare) ~\ F3. Heart (part of the ventral vessel) Chorda-animals 



V F 4. Heart, with auricle and ventricle Monorhina 



4. Fourth Stage in the Evolution of Organs. 



IV. Skeleton and Sexual Systems. 



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



(G\. Simple notochord Chorda-animals 



IV. G. Skeleton -system ) G2. Cartilaginous primitive skull Monorhina 



(Systema skelttare) "j G 3. Gill-arches, ribs, limbs Selachii 



\G1. Limbs, with five digits Amphibia 



rHl. Simple hermaphrodite glands Chorda-animals 



IV. H. Sexual system J HI. Distinct testes and ovaries Acrania 



(Systema sexuale) "j H 3. Seed-duct and oviduct Selachii 



KHi. Phallus (penis, clitoris) Protamnia 



39 



