46S 



♦ KNOWLEDGE ♦ 



[Dko. 15, 1882. 



see the following things : firstly, a numlipr of round spaces. 

 These are the ends of tulys or canals cut across. Thev are 

 naniod //oivrsi-in aiiiaf.i (after Clopton Havers, their dis- 

 coverer), and in the living state contain the larger Itlood- 

 vecsels of the bone. Secondly, around these I/ori'r.iirtn 

 canaU we note a series of irregularly-shaped spaces 



Tig. A. — A tranttvprso Bcction of bone in the neighbonrhood of two 

 Harvraian canals, i/, U; a lacano). Magnified about 250 



arr&nged in concentric circles. These spaces are called 

 lacmut. Thirdly, leading from one lacuna to another, and 

 also connecting the lacuna: with the Haversian canals, are 

 a number of fine lines, which are, in reality, channels. 







<'- 4 



Fig. B. — Lacnnic, a, and canalicnii, h. MagniCed about COO 

 diameters. 



These are called r/ninlimli. Tlie lacuiun measure about 

 the eightwnhundredth part of an inch in length, and the 

 eaiialini'i a fifteen-thousandth of an inch in diameter. If wo 

 imai^ine the Innin'r to be a sf-ries of lakes, the rnnalii-vH 

 will represent small rivers which connect the lake-systems. 

 Between the lakes and their rivulets is the mineral sub- 

 ■tance of the Vione, chiefly consisting of p/w.tji/iatr of liw.i'. 

 Now, what, it may be asked, do the lannur and raim'irnH 

 contain in a living bone ? 'JTie Haversian canals we have 

 ■e'-n to protect the bloodvessels which noiirisli the bone. 

 The laniurr contain each a small mass of living ;>r<^//r>;)/«j(m 

 — the universal matter of life— forming thn hmu-re/l. From 

 e«ch bone cell, lodged in its hicun, there passes along the 

 cannlicuH fine threarls or processes of this jelly-like proto- 

 plasm. Thus the protoplasm of one Incima is brought into 

 connoction with that of the other spaces ; and the whole 

 living Hu*>iitance of the lione forms a continuous meshwork 

 of minute c<-lls and fine fibres. Little wonder is it that, 

 thus filh-d with lining matirrial, Iwne should demand a rich 

 ■upply of nourinhment in the shape of blood. 



Bone, when analyse*!, in fonnfl to consist of an avimnl 

 part and a mineral part The animal part consists chiefly 

 of ytalinc. The mineral part is largely phoHphale of Hrne, 

 or •' Vione earth," with a little rhnll: {cirhonalf. of fiw) and 

 other minerals. We learn from this fact how important 

 for the young and growing Wly it must be to obtain in 

 the food a due supj.ly of lK)ne-forming materials. From 

 brwd, porridge, water, and like foo<U we oV»tain the minerals 

 for Vione-growth. Rickety children have bones 



in which the process of nourishment has not been duly 

 carried out, and hence arises the deformities to which these 

 children are so liable. In early life the bones contain a 

 larger proportion of animal matter than in old age, when 

 they become brittle and easily broken from excess of the 

 mineral constituents. If we soak a bone in a weak acid, 

 the acid removes the mineral part, and leaves the animal 

 part untouched, the bone retaining its shape, but becoming 

 lithe and flexible. 



"How and from what is bone developed?" is a question 

 of much interest The /ovtj bones of our bodies are " laid 

 down," so to speak, in (/ri.s^/fl or nnViAr^/c as their foundation. 

 The jl'it bones, such as those of the skull, are formed from 

 t'lhrous mfmhrane. Cartilage, which is the matrix or 

 " mother-tissue" of long bones, consists essentially of minute 

 cells, set in a structureless layer. Where bone is to be 

 formed, these cells arrange themselves in long, parallel rows, 

 and multiply rapidly in numbers. Then comes the process 

 of calciliciithm, or that by which the living niattiT, derived 

 from the blood, is thrown in amongst the cells, and invades 

 the cartilage. Thus lime is provided for the formation of 

 the bone. The further changes which take place in the 

 growth of the bone, consist in the formation of a thin layer 

 of spongy bone, which consists of hoiie-rcILt containing 

 living protoplasm, and which has been produced by the 

 under surface of the periosliiim, or layer covering the 

 bona These bone-cells in turn develop lime around them- 

 selves, so that naturally, a ring or circle of these bone- 

 cells will form a layer of bone, embedded in which wo find 

 the living protoplasm in spaces which will liecome the 

 lacuna' of the full-grown bone. The spaces in the centre of 

 the circles of bonc-cclls will become in like manner the 

 lldi-emian riinnh oi the adult bone. Meanwhile, outside 

 the bone, the periosteum continues its work of bone-for- 

 mntion, the thickness of the lx)ne being thus ensured and 

 increased ; whilst later on, the himnui; or spaces which 

 are set widely apart in the young bont^ appear more closely 

 set, owing to the growth which tills up the interspaces, and 

 which adds to the solidity of the structure. 



Bones begin to grow usually at several points in their 

 substances. These points arc the " ossifying centres." For 

 instance, a long bono, like the thigh bone, begins existence 

 as a more rod of gristle, and ends it as a dense solid bone : 

 its growth having taken place from three " centres " — one 

 in the shaft or column of the bone, and one for each end 

 thereof. When it grows in length, the increase takes place 

 at each end of the shaft ; for if two pins bo placed a little 

 way apart in a growing bone, the distance between them 

 does not increase, whilst the lione itself extends in length. 

 Removal of the end of a growing bone destroys its further 

 increase. 



Lastly, wc should note how the whole process of bone- 

 growth is one dependent on the living protoplasm of which 

 the Ijonc-ce/h are composed. Later on, we shall see how 

 the entire life of man — and necessarily that of other 

 animals — may bo truly described as the cumulotive result 

 of the growth and work of the.se minute living structures. 

 And no more wonderful thoiight can bo impressed on the 

 mind than that which shows us that, after all, human life, 

 as we know it, represents merely the activity of those 

 minute units which only the higher powers of the micro- 

 scope reveal to our understanding. 



Tri-kpiionk Wihf.8 in I5irtMiN(iHAM. — The Telephone 

 Company in Birmingham are negotiating with the Corpora- 

 tion for the laying of some of their lines underground. The 

 work will be begun by placing und(;rgroui]d the wires now 

 crossing Stephcnson-place. 



