( 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 I. Simple exoderm Gastraeads 



I. A. Skin-system 14 2. Outer skin (Skin-sensory layer) and),,, _ 



(Systema dermale) ) leather skin (Skin-fibrous layer) f " l 



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



is 1. Simple entoderm Gastraeads 



B 2. Intestinal epithelium (Intestinal-glan- \ 

 dular layer) and intestinal muscular J Worms 

 skin (Intestinal-fibrous layer) ) 



B 3. 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. 

 IT r -WonrA I 01 - u PP er throat ganglia Primitive Worms 



(^frmawrveum) I C2 ' Sim .P le medullary tube Chorda-animals 



6 ""v ( C 3. Brain and spinal marrow Monorhina 



II D Muscle system ( Dl " Skin - muscle pouch Primitive Worms 



<%*****> UigafflflSJSSSf nshef 



3. THIRD STAGE IN THE EVOLUTION OF ORGANS. 



in. Kidney and Vascular Systems. 



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



!S I. Primitive kidney canala Scolecida 



E2. Segmental canals Acrania? 



3. Primitive kidneys Monorhina 



4. Permanent kidneys Protamnia 



(PI. Simple coelom Scolecida 



III. P. Vascular system J F2. Dorsal and ventral vessels Worms 



(Systema vasculare) ] F 3. Heart (part of the ventral vessel) Chorda-animals 



I .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, ono after the other, in the Chordonia-ancestors. 



(61. Simple notochord Chorda-animals 



IV. G. Skeleton-system J G 2. Cartilaginous primitive skull Monorhina 



(Systema skeletare) 1 G 3. Gill-arches, ribs, limbs Selachii 



I G 4. Limbs, with five digits Amphibia 



fffl. Simple hermaphrodite glands Chorda-animals 



IV. H. Sexual system J #2. Distinct testes and ovaries Acrania 



(Systema sexuale) ~) H3. Seed-duct and oviduct Selachii 



(Hi. Phallus (penis, clitoris) Protamnia 



