STUDIES IN THE DEVELOPMENT OF THE RABBIT BY RICHARD ASSHETON, M.A. Reprinted from the Quarterly Journal of Microscopical Science' for LONDON: PRINTED BY ADLARD AND SON, BARTHOLOMEW CLOSE, E.C., AND 20, HANOVER SQUARE, W. 3. On the Causes which lead to the Attachment of the Mammalian Embryo to the Walls of the Uterus. (With Plate 19) 4. The Primitive Streak of the Rabbit; the Causes which may deter- mine its Shape, and the Part of the Embryo formed by its Activity. 191 A Re-investigation into the Early Stages of the Development of the Rabbit. By Richard Assheton, M.A. With Plates 13-17. INTRODUCTION. Ir is now nearly fifteen years since Ed. van Beneden1 published his account of the development of the early stages of the rabbit; and although I do not see that one can as yet describe every detail of even the earliest embryology of the rabbit strictly epigenetically, still it seems probable that van Beneden took far too little heed of the extrinsic causes which may direct the course of development. The effect upon the development of the presence or absence of such structures as the albuminous layer or zona radiata has been almost entirely ignored, apparently because they are matter outside the ovum. So, again, the size and structure of the uterus have hardly received their proper share of attention. The present paper and my other "On the Causes which lead to the Attachment of the Mammalian Embryo to the Walls of the Uterus," tend, I hope, to show how many of the details of the earliest stages may be ascribed to the direct maternal influences. That is to say, the inherited force is an energy 'La maturation de l'œuf,' &c., Bruxelles, 1875; "La formation des Feuillets chez le lapin," Arch. de Biologie,' vol. i, 1880. ، VOL. 37, PART 2.-NEW SER. H 77 686445 |