DOUBLE HEXS' E(;(;S 



21 



Although m the present state ot our knowlcilac it is iiiipossihle 

 to assipi a cause for the settiii<j;-iii ot iiiiti|H'nst;iIsis. it seems to 

 be a process that niav occur not onlv once Wiit even twice m the 

 envelopiiifj ot a volk. Dav aiiH- i (>!, p. _'.57' (piotcs a ca^c in which 



shell meinhraiic, and a thin shell nuMiihratic, and a •second case 

 is given l>v Laiidois i j). .M i ot an c<:'u' ot the red-ltacked shnke 

 {LaninscoUurio [.. ) that had tliree >liells one within tlx- other. 



So far as 1 know, the onlv ol-j.-etiun that has Keen raised aiiainst 

 antiperistalsLS of the ovidiu t haxoine troni Rahaiid ( AVI. j). 201 !. 

 who claims that tins proce» could not hnnix t^vo coys hx/cfhcr. 

 but would simplv move tliein up or down the oviduct. Ihit Mich 

 an objection is formal rather than otherwise, for it must he evident 

 to anyone who has watched the process as it ocdii^ m iIk iiu. ^ 

 tines that its local character is such that eggs could ea>ilv he made 

 to approach in the oviduct tlirouirh its mean.s. 1 therefore .ii>- 

 missthisol.i,-cti<.n a> without weiuht. 



believe that the formation ..t incloM-d en-Ps ,aiinoi take place 



simply by the undue retention of one e-u' till it is overtaken l.v 

 another, as stated m the second hvpotluvsis. hut that m all mstances 



