. On boneformation, its relation to tension and pressure;. d differentiation in growing bone ; andif the decrease of hmesalts in pre-formed bone may beidentified with the retardation of differentiation in growingbone, the general rule may be established that injuriousinfluences evoke a retardation and retrogression ofdifferentiation both in growing and in pre-formed bone. In the treatise just quoted we havestudied the longitudinalgrowth of bones^—with regard to functional pressure—ofnormal skeletons and of those whose power of growth isenfeebled by injurious influences, and have tried to givea
. On boneformation, its relation to tension and pressure;. d differentiation in growing bone ; andif the decrease of hmesalts in pre-formed bone may beidentified with the retardation of differentiation in growingbone, the general rule may be established that injuriousinfluences evoke a retardation and retrogression ofdifferentiation both in growing and in pre-formed bone. In the treatise just quoted we havestudied the longitudinalgrowth of bones^—with regard to functional pressure—ofnormal skeletons and of those whose power of growth isenfeebled by injurious influences, and have tried to givea graphical representation of the facts they present. Init we obtained the curves of Fig. 52 by noting downfunctional pressure on the horizontal, growth on the vertical 88 axis. In this figure, curve I represents the growth ofthe normal skeleton ; // that of skeletons that have beenslightly injured, , those showing slight feebleness ofgrowth ; /// that of skeletons which have been seriouslyinjured, , those showing serious feebleness of Fig. 52 Now it may be considered probable that, oil the whole,these curves are also applicable to pre-formed bone inthese skeletons : Bone formed during severe feeblenessof growth has, as is well known, a shortage of lime salts,which may last for a longer or shorter period. Such boneis obviously more sensitive to functional pressure thannormal bone. Therefore, if we may assume that on aconstant increase of functional pressure the quantity ofbone formed in normal bone diminishes after an optimumof pressure is exceeded, it is patent that in soft bone thedescent of the curve begins at less pressure. In soft bone,moreover, the ascent of the curve will be steeper than innormal bone, as well as the descent. 89 So, if the quantity of bone formed in normal skeletalparts on a constant increase of functional pressure, isrepresented by curve / of Fig. 53—pressure being notedon the horizontal, the amount of bone formed on thevertical ax
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbones, bookyear1920
