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Show 238 TJlR CRANIAL CJTARACTRRISTICS From the Mortonian collection, other i11ustrations of this fact might be dmwn; but neither space nor Lime permits their introduction hcl'c. In the study of the sutures, considerations of a highly philosophical chamctcr arc involved. Their history enables us to perceive wby the crn.nium was not formed of one piece, and why there should be two frontal and two pari tal bones, and only ouo oceipitnl Such an arrangement obviously allows the fullest development of the anterior and middle lobes of the ccrebrum,-the organs, according to OAR US, of intellig nee, reflection, and judgmcnt.82 That tho sutures arc t.utamina el'ebri, that in tho footus they permit tho cranial bones to overlap during parturition, ·and thus, !Jy diminishing the size of the h ad in certain of its diameters, and producing anrosthesia, facilitate labor, curtailing its difficulties and diminishing its dangers to both mother and child, thoro can be no doubt. Such provisions arc of high iutorcst, as exhibiting the harmony of nature. But when we call to mind that tbo sl ull is a vertebra in its highest known state of development; that the enclosed brain, as the organ of intellection, is tho distinguishing mark of man; that the development of tbo cranium goes on pari passu with that of the encephalon; that tho various degrees of human intelligence arc definitely related to certain permanent skull-forms; and that the cranial sutures, in conjunction with the ossific centres, are tho guiding agents in tho assumption of those forms-it will be evident that a high r and far more comprehensive significance is attached to these bony intcrspaccs. Again, no extended investigation has boon instituted, as far as I am aware, to determine the period at which the different cranial sutures arc closed in the various races of men. 1'ho importance of such an inquiry becomes apparent, when we ask om·solves tho following questions :-1. Docs the cranium attain its fullest dev lopmcnt in all the races at the same, or at different periods of life? and 2. To what extent are race-forms of the cranium dependent upon the growth and modifications of the sutures? " 1'he most obvious usc of tho sutures," nccording to Dr. Morton, "is to subsorvc the process of gt·owth, which they do by osseous depositions at their ma1·gins. llonco, one of thc~o Bultu·cs is oquivnlent to the interrupted structure that exists between tho shaft and epiphysis of n. long bono in the growing stn.to. 1'hc shaft grows in length chiefly by accretions fit its extremities; and tho epiphysis, like tho cmnial suture, disappears whou the perfect development is accomplished. Hence, we may infer thn.t tho skull ceases to expand whenever tho sutures becomo consolidated with the proximn.te bones. In other words, the g1·owth of the brain, whether in viviparous or in oviparous animals, is conscntnneous with that of the skull, o.ncl neither can be developed w.ithout tho presence of free suturcs."Sil 82 "Dna boaondoro 01·go.n des orkenneuclon, vorgloiohonden unci urthoilondon Ooistosloben." - Symbolik der mcn.•chlichm Gestalt, von Dr. C. G. Co.rua, Leipzig, 1868. 83 Soc article on Size of the Bro.in, &c., quoted above, p. 808. OF TIIR RACES OF llfEN. 230 From investigations of this nature, and ft·om other considcrationt:l, Dr. M. conclud d that the growth of tho brain was arrested. at tho adult ago, that tho consolidation of the sutures was an indication of the full development of both cranium and brain, and that any incron. Re or decrease in tho size or weight of the brain after the adult period would not be likely to affect tho int l'llal capacity of tho cranium, which, therefore, i ndicatos tho maximum size of the encephalon at the time of its great st devolopm nt. OoMBiiJ, however, aftirms that when the brain contracts in old ago, tho tabula vitrea of tho cranium also contracts, so as to keep itself appli d to its contents, tho outer 01' fibrous table undergoing no chango.s1 It is, to some exton t, true tbat in tho very aged, even when tho skull-bones become consolidate<l into on piece, some changes may result from an undue a tivity of tho absorbents, or some defect in the nutritive operations. Under such ir •umstancos, the cranial bones may bo thinned and ~:tlt r d slightly in form. DAVIS gives an example of this chango, in tb shtll of an aged Chinese in his collection, in whieh the central area of the parietal bones is thinned and depressed over an xtcnt equal to four squar inches to about one-third of an inch deep in tho central part.85 Such changes, however, arc too limited in their extent to demand more than a passing notice. Tho pressure of the brain, exerted through its weight, is felt mainly upon tho base and inferior lateral parts. Prof. ENGEL, in a valuable monograph upon sknll-forms,86 particula, J:]y calls attention to the action of tho muscles in dctom1ining those forms. lie consid rs the influence oftho oc ·ipito-frontalis as almost inappreciable,- so slight, indo d, tltat it may be negl ctocl in our inquiries. 1'ho action of the temp ral and pterygoid muscles and of tho group attach d to the occiput, though more evident, is still not worLhy of mnch consiclel'ation. To the action of tho musculus stomo-cloido-mastojdous, he assigns a greater value. "This muscle," snys he, "tends to produce 11 downward displacement at tho mttstoid portion of the tomporo.l bono, which will be tho more consicl mblo, o.s tho lower point of its attncbmont- the sternum nnd clo.vicle- is o.ble to ofl'or much greo.ter resistance thnn the upper. In addition to this, the unusual length of tho muscle produces, by its coutmclion, more cffoct, 11nd, hence, favors a grot1tor displacement of tho bones to which it is o.ttachod. 1'ho bono upon which it cxct·ts its inUucnco is also vo,·y loose in ont'ly lifo, and oven during tho first ycn.r of om· exist nco, when extonsivo motions of tho muscle alrcn.dy take pl>tco, it is not as !it·mly fixed as tho other bones; houco, it becomes probn.blc thn.t tho influence of this muscle upon the position of tho bonos of the Pkull will bo o. dcmonstrnblo one. "It may, however, bo admitted a priori, that in spite of o.Jl these ftwomblo circnmstancos, M System of Phrenology, p. 88. 1!11 Cr. Drit., p. 6. Soc also Gall, "Sur los Fonctions clu Ccrvco.u," III, 63, 1826. 86 Op. cit. |