76 Translation from Purkinje 



§ 13 

 Of the chalaziferous membrane of Dutrochet. 



At first the chalaziferous membrane of Dutrochet* is assuredly al- 

 bvimen. In its progress through the oviduct it becomes solid and finally 

 takes on almost the same character as the vitelline membrane. The 

 internal whitish strand of the chalazae is the continuation of the 

 chalaziferous membrane and is prolonged from it to the interior of 

 the chalazae like a tube twisted on itself and closed by torsion, just 

 as if you were to invest a sphere with a membraneous sac open at both 

 ends and close it by twisting at both poles. 



The vitelline membrane itself remains unchanged and intact as it 

 was in the ovarian ovule. There is no communication through it with 

 the chalazal canal by which albumen might be conducted to the 

 [] 17 ] interior of the yolk.'"" The canal which Leveillef saw can be readily 

 demonstrated if you will but cut across a chalaza under water. The 

 demonstration is successful only in chalazae which are doubly twisted 

 on themselves so that the mutually opposed turns necessarily form 

 an inner canal like the modiolus of the cochlea. This nevertheless does 

 not communicate with the yolk in any way (fig. 22). Although the 

 vitelline membrane does not appear porous under the microscope, it 

 seems permeable everywhere to nutrient fluids, just as is the case in 

 the ovarian ovule where it takes blood from the vascular [thecal] 

 membrane, transfers it to the interior and converts it into yolk mate- 

 rial (fig. 22*). We see the same thing happen at the beginning of the 

 development of the chick when the albumen above the cicatricula 

 disappears and enters the interior, producing a crater. We readily 

 infer, therefore, that a similar thing probably happens to albumen 

 over the whole surface of the vitelline membrane; there is no need 

 to conjure up suctorial ducts. It is not difficult to separate the chala- 

 ziferous membrane from the underlying vitelline membrane in the 

 place where the chalazae are inserted, even where that part of it which 

 is twisted into a strand opens up in the [chalaziferous] membrane. 

 To do this successfully you should take the chalaza near its vitelline 

 root with a pair of volsella forceps and at the same time cut from the 

 yolk hanging below it a piece of the vitelline membrane, wash it, and 

 then, under a medium-power lens tear the two membranes [vitelline 



* Joiir7ial de Physique \de Chimie, d'Histoire Naturale et des Arts], Vol. 88, p. 

 170 [to 178, 1819:— Henri Dutrochet: "Histoire de I'oeuf des oiseaux avant la 

 ponte." Translation in Deutsch. Arch. f. Physiol. 6:379-385, 1820.]. 



f Reils Archiv [/»r die Physiologic], Vol. 4, p. 418 [1800; this is an abstract of 

 J. B. F. Leveille: "Dissertations physiologique sur la formation des foetus dans les 

 mammifdres et dans les oiseaux" /. de physiq., de chim., d'histoir. natiir. et d. arts, 

 Ann. 7 de la Republique (1799), p. 386]. 



