SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 



VOL. 35, NO. 3, PL. A 



Fio. A 



Round Jacuna with short, bushy canaliculi.' 

 E'arly stage 



Fio. B 



Oval lacuna with short, bushy canaliculi. 

 Later stage 



THREE STAGES IN THE DIFFERENTIATION OF LAOUNTE 



Fig. C 



Long 1 , narrow lacuna with long-, straight 

 canaliculi. Latest stage 



Fig. D 



Basic or undifferentiated bone. Aniblystoma 

 tigrinum 



Fig. E 



DilVerenliated bone. Frog. 



Concentric lacunre 

 FIRST DIFFERENTIATION 



Fig. F 



Differentiated bone. Haversian system of man. 

 Concentric lamellae 



Fig. 1 



First type. Frog 



Fig. 2 

 Second type. Turkey 



Fig. 3 

 Third type. Man 



