SMITHSONIAN CONTRIBUTIONS TO KNOWLtUUE 



VOL. 35. NO. 3. PL. A 



Fig. a 

 Round lacuna with short, bushy c-analiculi. 



Early stage 



Fia. B 



Oval lacuna with short, bushy oanaliculi. 



Later stage 



TllUEE STAGES IN THE D1FFE.KEMTIATI0N OF LACUN.'K 



Fio. C 



I/ong, narrow lacuna with lonp, straight 



canaliculi. Latest stage 



Fig. D 



Basic or undifferentiated bone. Aniblystonia 



tigrinuin 



Ftg. E 

 DiiTcrenlialod bone. Fi'og. Concentric liicuiis 



URST DIFFERENTIATION 



FlQ. F 



Diffcicntiated bone. HaverBian system of man. 



Concentric lamellje 



Fig. H 



Early stage in the differentiation of laniinx. 



Aztec jay 



Later stage in the differentiation of lamiii5e. 

 Chinese pheasant 



SECOND DIFFERENTIATION 



Fig. J 



Latest stage in the differentiation of lamina;. 



Pig 



Xj 



m^^cm 



^i^e. 



^--« 



.«:>:■* .■■■ 











Fig. K 

 Stage la. Amphibian 



Fig. L 

 Stage lb. Reptile 



Fig. M 

 Stage Ic. Bird 



Incomplete differentiation of Haversian systems 



THIRD DIFFERENTIATION 



Fig. N 



Stage C Mammal. Man. 



Complete differentiation of 



Haversian systems 



Fig. O 



Haversian system 



formed in the mesh of 



cancellous bone 



Fig. P 



Haversian systems 



formed in the canala of 



a second type bone 



ABERRANT FORMS 



Fig. 1 

 First type, .'rog 



Fig. 2 

 Second type. 'I'urkey 



Fig. 3 

 Third type. Man 



