1848.] 117 



filleJ up by a deposite of osseous granules, and while this deposite is going on, 

 small cells are left, which are the rudimentary Purkinjean corpuscles, Henle 

 thinks them to be the cavities of cells, the thickened walls of which are pierced 

 by the canaliculi. Hassail confirms the view of Schwann, by stating "the 

 bone cells (Purkinjean corpu=cles,) are to be regarded as complete corpuscles, 

 the canaliculi of which are formed by the extension of the cell wall, which is 

 proved by watching the formation and development of bone." 



The opinion of Schwann and Hassail I can fully corroborate from my own 

 observations upon an ossifying frontal bone, from a human embryo measuring 

 two inches from heel to vertex. Each lateral half of the bone is about 3^ lines 

 in diameter, and presents to the naked eye the appearance of a delicate and close 

 net-work, arising from the numerous areolae occupied by temporary cartilage. 

 The frontal and orbital plates, it is worthy of incidental remark, at this period, 

 are nearly on a plane with each other, or are connected together at a very obtuse 

 angle along a central, transverse, crescentic, raised line, the rudimentary 

 supra-orbitar ridge. 



The mode of development of the Purkinjean corpuscle, as noticed upon the 

 upper or posterior border of the os frontis, is briefly as follows: After the 

 primitive ossific rete has been formed from the deposite of the osseous salts, 

 enclosing groups of cartilage cells in the areolae, the further deposite takes place 

 in a fibrous or line-like course from the parietes of the areohe of the primitive 

 osseous rete, in the interspaces of the cartilage cells nearest to, or in contact 

 with the sides of the areolrn. At this period the cells shoot out or extend their 

 canaliculi between the fibrill.e just formed, and then the cell-wall and continuous 

 walls of the canaliculi fuse with the translucent, homogeneous, or hyaline sub- 

 stance of the cartilage existing between the cells and the osseous fibrillas, and 

 with the fibrillfc themselves, by the deposite of the osseous salts. The period 

 of the formation of the canaliculi appears to be quite definite, occurring during 

 the deposite of the osseous salts, and not before. To such an extent is this the 

 case, that I noticed in several instances cells which had formed their canaliculi 

 upon the side which was ossified, while upon the other side F could not distin- 

 guish any trace of them. 



During the whole time of the formation of the Purkinjean corpuscle, the 

 nucleus remains unchanged ; at least no change is perceptible in it beneath the 

 microscope, and by applying tincture of iodine to the preparation, which turns 

 the nucleus brown, I was able to detect it within the perfected Purkinjean cor- 

 puscle, not only corresponding to the nucleus of the remaining unossified cartilage 

 cells in granular structure, but also in its measurements. After the Purkinjean 

 corpuscle has been formed a short time, the nucleus dissolves away or disappears. 



The newly formed Purkinjean corpuscle is about the same size as the remain- 

 ing unossified cartilage cells, as indicated in the list of measurements appended 

 to these notes. 



Size of cell of temporary cartilage, from the unossified os frontis of a human 

 embryo, i of an inch: nucleus of do. __i of an inch ; nucleolus ^ 



•''l886_ 3 125 833T 



of an inch; Purkinjean corpuscle _i of an inch; nucleus within the same 



18 6 5 



^ «__ of an inch. 

 7(7,3 



2. On the intimale slruclure nf articular cartilage — .As is familiar to every 

 anatomist, articular cartilages always fracture in a direction perpendicular to 



