20 



STRUCTURE OP 



Fig. 1.* 



puscules or with the corpuscules themselves. Among tlie concen- 

 tric lamellae of the Haversian canals, the tubuli are given off from 



the surfaces, lying in contact 

 with the lamella?, and they 

 proceed straight through the 

 * lamellae in two directions, 

 inwards towards the area of 

 the Haversian canal, or out- 

 wards towards the outer- 

 most lamellae. If in their 

 course the tubuli meet with . 

 another corpuscule, they ter- 

 minate in it or communicate' 

 with its branches ; but the 

 direct course of the tubuli 

 towards the centre is never 

 interfered with. So eyident 

 is the tendency of all the 

 tubuli to attain the centre, 

 that in several corpuscules 

 situated between the outer- 

 most lamellae, I have ob- 

 served the tubuli from the external surface to curve around the ex- 

 tremities of the corpuscule, in order to proceed with those given off 

 from the internal surface, to their central destination. From their 

 general appearance in relation to the lamellae, these tubuli seem to 

 me to deserve the title of converging tubuli ; they all proceed 

 towards the central canal, and those which reach that destination 

 terminate upon its internal surface. The trunks of the tubuli not 

 unfrequently give off one or two branches. As regards their form, 

 the tubuli are undoubtedly cylindrical, and they probably contain 

 calcareous substance, as do the calcigerous tubuli described by 

 Muller. 



The, lines remarked by Deutsch are, therefore, according to my 

 observations, cylindrical tubuli, traversing the concentric lamella) 

 of bone, communicating with the* corpuscules, and with the cavity 

 of the Haversian canal, and identical with the calcigerous tubuli of 

 Muller. 



In the fresh state bones are invested by a dense fibrous mem- 

 brane, the periosteum, covering every part of their surface with the 

 exception of the articular extremities, which are coated by a 



* Minute structure of bone, drawn with the microscope from nature, by Bagg. 

 Magnified 300 diameters. 1. One of the Haversian canals surrounded by its concentric 

 lamellce. The corpnscules* are seen between the lamellae ; but the converging tubuli 

 are omitted. 2. An Haversian canal with its concentric lamellae, Purkinjean corpus- 

 cules, and converging tubuli. 3. The area of one of the canals, 4, 4. Direction of the 

 lamellae of the great medullary canal. Between the lamella at the upper part of the 

 figure, several very long corpuscules with their tubuli are seen. In the lower part of 

 the figure, the outlines of three other canals are given, in order to show their form and 

 mode of arrangement in the entire bone. 



