XII. ON THE STRUCTURE AND DEVELOPMENT OF THE 

 VERTEBRATE OVARY*. 



(With Plates 24, 25, 26.) 



THE present paper records observations on the ovaries of but 

 two types, viz., Mammalia and Elasmobranchii. The main points 

 dealt with are three : i. The relation of the germinal epithelium 

 to the stroma. 2. The connection between primitive ova in 

 Waldeyer's sense and the permanent ova. 3. The homologies 

 of the egg membranes. 



The second of these points seems to call for special attention 

 after Semper's discovery that the primitive ova ought really to 

 be regarded as primitive sexual cells, in' that they give rise to the 

 generative elements of both 'sexes. 



THE DEVELOPMENT OF THE ELASMOBRANCH OVARY. 



The development of the Elasmobranch ovary has recently 

 formed the subject of three investigations. The earliest of them, 

 by H. Ludvvig, is contained in his important work, on the 

 ' Formation of the Ovum in the Animal Kingdom V Ludwig 

 arrives at the conclusion that the ovum and the follicular epithe- 

 lium are both derived from the germinal epithelium, and enters 

 into some detail as to their formation. Schultz 3 , without appa- 

 rently being acquainted with Ludwig's observations, has come to 

 very similar results for Torpedo. 



1 From the Quarterly Journal of Microscopical Science, Vol. 18, 1878. 

 - Arbeit en a. d. zool.-zoot. Instil ut Wiirzburg, Bd. I. 

 3 Archivf. micr, Anat. Vol. xi. 



