1 8 1 6.3 Medical and Chir 



and third phalanges. The diameters of 

 these irieces of bone were much la!2;cr, 

 ia proportion to the lengtli of those 

 parts of flie limbs within which they 

 were forming, than at the fntuie stages 

 of their growth. 



This was most evidently the case in 

 the bories of the hand and loot : it aji- 

 peared to be a provision for admitting of 

 a considerable increase to tiif.' length of 

 the cylinder, before it became necossar)' 

 to enlarge its diameter. 



Exam. 2. In tiie embryo ten weeks 

 old, the extremities of the bones were 

 found connected together by u cartilagi- 

 nous substance. 'I'he rings originally 

 formed having, in the mean time, gra- 

 dually increased in length, had now 

 reached the cartiiagiiions portions at the 

 extremities, "i'he cartilage comiecled 

 lo the upper end of the bone of the arm 

 was divided into thin sections, for exa- 

 mination under the microscope. .Seve- 

 ral irregular cavities were discovered in 

 the substance of the cartilage, filled with 

 a rancilaginons fluid. In one of these 

 sections a smooth cavity was detected, 

 which extended into an even canal or 

 tube, passing down to the surface of 

 xiiiion, between the cartilage and the 

 J)one. 



Exam. 6. In order to ascertain more 

 clearly the primary arrangement of the 

 ossific matter, the lowei extremity of the 

 thigh-bone of a child, three weeks old, 

 ■was macerated and cleaned. A longi- 

 tudinal section of the bone was then 

 made, and the surface of the section, in- 

 cludhig the margin of ossification, pared 

 very smooth w ith a kniie, 'J'he piece 

 was afterwards cakined, with a view to 

 remove the remaining animal matter. 



In the examination of tiiis, and many 

 successive sections of a similar descrip- 

 tion, it was observed that, in proceeding 

 from the middle of the c}lindrical boues, 

 where the medullary spaces are larger, 

 and the cancellated structure stronger, 

 towards the nu)re recently formed cxire- 

 luities of the bone, the ossific masses be- 

 come more numerous, of a lighter sub- 

 stance, and a thinner textin-e; the same 

 gradation being continued uj> to the 

 margin of the newly ossilied surface, 

 ■where the structure is most curiously 

 uroughl, and so exquisitely fine as 

 scarcely to admit of d('scrii)tion. 



From these examinations it was 

 ascerlaiuid that the first and earliest 

 Blate in which the particles of ossilic 

 matter become ap|)arent, after they have 

 formed a mass by their cohesion, may 

 JttO cunoldcrcd ax an asseinblaive of Ihu 



'urgical Society. 243 



finest and thinnest fibres, monlded into 

 the form of short tubes, arranged nearly 

 parallel to each other, and opening ex- 

 ternally upon the surface connected wiUi 

 the cartilage. 



Exam. 7. In order to observe the 

 clianges that occur towards the latter 

 periods of growth, sections were taken 

 from the lower end of the thigh-bone ; 

 these were selected from subjects of va- 

 rious ages, and the following were th« • 

 appearances under the microscope. 



In a child eleven months old, the ca- 

 nals within the cartilage were very few 

 in number. At the age of four yeans 

 these canals were still moj'e thinly scat- 

 tered, and those that were observed 

 wore of comparatively small diameter. 

 ^V hen the sections became partially ' 

 dry, a line, one-sixteenth of an inch in 

 breadth, was sccu towards the margin 

 of ossification, where the particles of th« 

 cartilage had apparently taken on a new 

 arrangement, so as to resemble parallel 

 lines or fibres. This curious circum- 

 stance has been noticed by Haller. 



At the age of eleven years the cartila- 

 ginous canals were found to be still di- 

 minishing both in point of size and 

 muTiber ; and in the examinations made 

 at seventeen years, it was with great dif- 

 ficulty that a section couhl be found in 

 which thete was any remaining trace of 

 them. 



Exam, 8. Sections taken from the 

 cartilages and ossifying extremities of 

 the bones of the slink or foetal calf, were 

 examined in the microscope. The car- 

 tilaginous canals were fouiM to be very 

 numerous. They were all filled with a 

 clear mucilage, and the sides of the ca- 

 nals in many parts of the cartilage had 

 the appearance of being stained with 

 blood, although no distinction of blood- 

 vessels could be iletectcd in !^ny of 

 them. 



By a series of these examinations it 

 was ascertained, that the cartilages ui)on 

 which the flat bones of the scapula and 

 ilium are produced, possess a similar or- 

 ganization to that which obtains ia tii* 

 c}lindrieal bones. 



'Jlie p(jsterior extremities were in- 

 jectwl with coloured size, and the carti- 

 lage then examined in sections, under 

 the microscope. 'J'he membranes co- 

 vering the cartilages and bones exter- 

 nally were beautifully injected; the ca- 

 nals wiihin the cartilage also wero 

 equally well injected. Wherever the 

 canals appeared, Ihcy were observed to 

 have received the verinilliori. ' "• ' 



.Sc\vial oblique sections of canals fell 

 \ i ii ijiidtu'- 



