NO. 10 THE CIRCULATORY SYSTEM IN BONE FOOTE 1 5 



the Others. As soon as the blood vessels pass through the external 

 surface of the bone they send off branches into the planes of their 

 divisions and form the branching distributions there. 



TANGENTIAL SECTION OF THE INNER TABLE OF THE SAME FRONTAL 

 BONE, SHOWING THE CIRCULATION 



Pl. 5, Fig. 40 

 In this section the bone is perforated by numerous entering canals 

 with and without enclosing lamellae. The blood vessels from the 

 cerebral surface enter the bone by these canals and find their way to 

 the diploe. The circulation within the bone is branching in type and 

 situated nearer the cerebral surface than the diploe. Many vascular 

 expansions are present with their incoming and outgoing vessels. 



TANGENTIAL SECTION OF THE OUTER TABLE OF A HUMAN 

 PARIETAL BONE, SHOWING THE CIRCULATION 



Pl. 5, Fig. 41 

 The section is taken from the central portion of the bone. The 

 type of bone is first. Entering vascular canals surrounded by lamellae 

 are numerous. The circulation is branching in type. Vascular ex- 

 pansions are large and numerous. Those in the center give the im- 

 pression of distributing points in the circulation. 



TANGENTIAL SECTION OF THE INNER TABLE OF THE SAME PARIETAL 

 BONE SHOWING THE CIRCULATION 



Pl. 5, Fig. 42 



The section is situated nearer the cerebral surface than the diploe. 

 Entering vascular canals with enclosing lamellae are numerous. The 

 circulation is branching in type and not as dense as that of the outer 

 table. The vascular expansions are many and large. The type of 

 bone is first. 



TANGENTIAL SECTION OF THE SQUAMOUS PORTION OF THE 

 TEMPORAL BONE OF MAN, SHOWING THE CIRCULATION 



Pl. 5, Fig. 43 

 The type of bone is first. Entering canals with and without en- 

 closing lamellae are present. The circulation is branching in type 

 and the vascular expansions are large and very numerous. The ex- 

 pansions vary in size and frequency of occurrence in different sec- 

 tions. In some instances they are very small and few in number, in 

 others, large and numerous, and they are much more prominent in the 



