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THE AMERICAN NATURALIST [Vol. XL 



Admitting antiperistalsis to be essential to the formation of 

 inclosed eggs, it is interesting to observe that, notwithstanding 

 tlie migrations of these eggs, they appear to rc^taiii ah\a\.s the 

 same axial relations to the ovidnct that they had in \\\v Ix-uinning. 

 This is dearly seen in the eggs described bv Havn(>s i "C.:; i, ( "hobant 

 ('97), Herrick ('99b, p. 410), Kmistler et HiMM-i.sit ( OJ , and 

 Gruvel (:02), as well as in one of those described in this i>ai)cr, 

 in all of which the point of the inclosed egu' is in tlic (hrcction of 



smaller egg has retained its original axial ichitions to the o\iduct 

 even though it has moved in l)otli .iircctioiis tlironuli ihat iiibe. 

 Moreover, when the inclosed egg is so small tiiat it miuht lie cither 

 near the point or near the butt of the iiiclositig cuu', it docs as a 

 matter of fact (Barnes, '03; Herrick. 'll'.tb, |). 110; (.niv<-l. :02; 

 and Kunstleret Brascassat, :02) always lie near the pomt, showing, 

 since the egg moves through the ovidm t pomt forward, that it is 

 the second egg that incloses the first and not the rev(>rse. 



In one respect the egg obtained from Mr. Nielson is of special 

 interest. As I have already stated, it eoiitaine<l no yolk in either 

 the inclosed or the inclosing albumen, though traces of yolk sub- 

 stance occurred in the latter near the butt of the inclosed visi:. 

 This was due, I believe, to a ruj)tured and partially cseajx'il yolk. 

 If this explanation is true, is it po.ssible that the yolkless condition 

 of the inclosed egg is also due to the loss of its yolk? It seems 

 well established, however, that albumen can be formed in the 

 oviduct without the presence of a >olk P.^.iblx forei-n bodies 



duction of this material. \ on Natlm>iu-> "'.).'., p. (;:):> i ha- pointed 

 out that when a hen lays an eu--. tlH> dr-tal portion (.f the oviduct 

 is so far rolled out that foreign bodies may adhere to it and thus 

 be carried well into its eavitv. In this way chicken-yard refuse 

 and feather,^, .nch lia\e been noted by Landois ('S2, p. 23) in 



incorporation in a forming cnn- was possible. Tli(>^e and like 



Parasites are also known to make their wav into the ovidnct, 

 and, though what have been supposed to be tapt^worins in eggs 



