VIEWS OF PRIMITIVE MARRIAGE. 



203 



which, in consequence of the change of pressure, adjusts itself with the 

 faces of the prism. The deformed mass exhibits on a transverse frac- 

 ture an essentially schistous texture, which 

 is thus disposed : in all of the part inclosed 

 between the plates, the leaves are nearly 

 parallel to the two walls, but in the part 

 which passes beyond the plates the leaves 

 bend over and diverge from the axis so as 

 to be parallel to the two exterior surfaces, 

 while they themselves separate more and 

 more. The leanness is especially marked 

 near the two external surfaces ; it is gener- 

 ally much less so toward the central part. 

 This experiment furnishes a fac-simile (Fig. 

 1) of the leafy structure called fan-shaped. 



It remains to call attention to the con- 

 sideration of the mechanical actions devel- 

 oped in the crust of the globe as the source 

 of the heat-movements to which the meta- 

 morphism of rocks is due. M. Daubree has 

 been led by his experiments to conclude that 

 such is the origin of this phenomenon. The 

 mechanical action which is required to make 

 rocks schistous is enough to heat them to a 

 considerable degree. It is known that a 

 very slight elevation of temperature is suffi- 

 cient to produce chemical reactions in the 

 depths of rocky masses. The quarry-water, 

 with which all the rocks are impregnated, and 

 that which finds its way to them through 

 fissures, could give rise to reactions which might be prolonged for a 

 protracted period. La Nature. 



Fig. 4. Production of the fan- 

 shaped structure in a mass of 

 clay forced to flow out from be- 

 tween two parallel plates. The 

 horizontal pressure of the plates 

 makes it take on first a leafy 

 structure, then the fan-shaped 

 structure as soon as it has passed 

 beyond the limits of the plates. 

 (One third the natural size.) 



-*r++- 



VIEWS OF PRIMITIVE MARRIAGE. 



Bt loeimer fison. 



THE theory now to be considered was first advanced by Mr. Mc- 

 Lennan, in his work entitled " Primitive Marriage." It will be 

 found stated in the following words in his " Studies in Ancient His- 

 tory," * a reprint, with additions, of the former work : 



"We believe this restriction on marriage (i. e., exogamy) to be 

 connected with the practice in early times of female infanticide, which, 



* " Studies in Ancient History," comprising a reprint of " Primitive Marriage." By 

 John Ferguson McLennan, M. A., LL. D. Quaritch, London, 1876. 



