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THE AMERICAN NATURALIST [Vol. XL 



shell-forming portion of the duct the operation seems to me to 

 necessitate antiperistalsis. It might be assumed that the inclosed 

 egg made its way into the albumen of the inclosing one by rup- 

 turing the shell membrane of the latter just as that egg reached 

 the shell chamber of the oviduct. Hut there is no evidence in 

 such eggs of a ruptured membrane as this hypothesis would recpiire 

 and indeed there is a case on record (Gruvel, :02, p. 73) in which 

 the inclosed egg apparently met the inclosing one when the shell 

 membranes of the latter were forming and, instead of rupturing 

 them, the inclosed egg remained between tlic iniK-r and outer uu-in- 

 brane and never entered the albumen of the iuclosinu- cug at all. 

 I therefore do not believe that the inclosed egg vi\{vv> the albunicu 

 by rupturing egg membranes but by meeting the iuclosinu < uu !)\ 

 antiperistalsis high in the oviduct and before the nuMiihrano ha\c 

 been formed. 



Another fact that seems to me impossible of explanation except 

 on the assumption of antiperistalsis is tlie occurrence of ■soft- 

 shelled" eggs in the body-cavities of fowls. This has l.c-ii re- 

 corded by Davaine ('61, p. 241) and more recently by Landois 

 ('99, p. 52), who states that in one instance he found fotir such 

 eggs in the body-cavity of a hen. Two of these were broken, but 

 two were whole and had all the a])j)earances of normal eggs e\ce|)t 

 that they lacked shells. As there is no sounv for the albumen 

 and shell membranes of the-e e-ii-. except th<- middl.' and lower 

 part of the oviduct and no way nUo the l)ody-( a\ ii v except l.v die 

 infundibulum, I believe the eonelusion inevitable that the^e eu^s. 

 after the formation of their shell membranes, were moved proxi- 

 mally by antiperistalsis. 



How antiperistalsis is excited in the oviducts is not understood. 

 It has been suggested that an egg of small voliune miuht induce 

 such a movement and thus be returned to the upper j)art of the 

 oviduct, but, though this cannot be denied, it nnist be nnnembered 

 that, as Landois ('().-,, p. :\2) has shown, small ^wh as are 



often found in laruv ones, mav l,e lai<l by l„-„s M.uvMv. r. a^ 

 wa. Mated in de^. ril.ing indoMMl (-n-. of the .ceond . la^-^, e^::^ -f 

 normal .i/e are often found uitliin the .hell niembiane. of ex. 

 sively large eggs and must therefore have moved up. tht> oviduct. 

 Hence the small size of an egg cannot be the onlv eau^e of anti- 

 P ^nstalsis^ if in f ac^^^ at all eff ective in this respect. 



