188 Professor Owen's Reply 



which relate more immediately to my claim to the discovery 

 of the allantois of the kangaroo. 



When I was first made acquainted with the attempt on the 

 part of M. Coste, to invalidate that claim, I sought to establish 

 the proof of my discovery on other evidence than bare recla- 

 mation ; and I appealed, in my previous letter to the Acade- 

 my, to the condition of the parts exhibited by me to M. Coste, 

 and which M. Coste had asserted to be an undissected ovum 

 of the kangaroo. I appealed, and I still appeal, to the ex- 

 tensively developed chorion, preserved in the Hunterian Mu- 

 seum of Comparative Anatomy, and demonstrating the con- 

 dition of a distinct membranous sac, but which M. Coste, 

 unluckily for himself, was induced to describe as being con- 

 founded with the umbilical vesicle. This chorion of the ovum 

 of the kangaroo, was, in truth, adherent by only a small pro- 

 portion of its internal surface to the umbilical sac, and the re- 

 sistance which this adhesion offered, I found little difficulty 

 in overcoming, (except at one point), when, in June, 1837, I 

 first dissected the ovum in question. 



M. Coste now confesses what he ought to have stated to 

 the Academy and to M. Blainville in his first letter, namely, 

 that he knew nothing of the chorion from actual observation, 

 but that the description he presented to the Academy as to its 

 condition, reposed solely on induction. "Lorsque nous avons 

 annonce quHl, fie chorion J, etait confondu avec la vesicule 

 ombilicale, nous n 'avons juge que par induction, et nous a- 

 vons cm avancer un fait que Inexperience et l'analogie nous 

 conduisent a soutenir :" — p. 15. 



Now what is the experience, and what the analogy, behind 

 which M. Coste seeks to shelter himself from the sentiments 

 which every honorable and impartial man of science must en- 

 tertain towards him, in reference to this imaginary description 

 and the motive which induced him to make it ? His expe- 

 rience respecting the chorion of the marsupial ovum, was li- 

 mited to the results of the dissection of a single ovum. In 

 my account of this dissection, (Philos. Trans. 1834), the cho- 

 rion is described and figured as a membrane distinct from the 

 umbilical sac. I there state that at the part where they ad- 

 hered together, the two membranes could be separated from 

 each other with a slight effort, except at the line of the vena 

 terminalis of the umbilical sac. Did this his sole experience 

 respecting the condition and relations of the marsupial cho- 

 rion to which M. Coste could appeal, justify him in his un- 

 worthy insinuation* with reference to the statement made by 



*"Sans chercher a penetrerles motifs qui ontpu determiner M. R. Owen 



