On the Female Organs and Placentation of the Racoon. 285 



decidua reflexa, the ridges became irregular, and were no longer dis- 

 tinguishable as continuous structures, but became broken up into 

 more or less elongated portions, the free margins of which were pro- 

 vided with papilliform eminences. This gradual dismemberment of 

 the continuous ridges could be clearly traced in passing from the 

 centre towards the margins of the placenta, inasmuch as the ridges 

 which were clearly continuous and regularly arranged, as above de- 

 scribed, at one part of the placenta, became less and less regular and 

 more tortuous at another part. The structure of these ridges, both at 

 the central and at the lateral margins of the placenta, is the same, and 

 differs widely from that of the papilla?, which they enclose. The 

 papillae I regard as belonging to the foetal portion of the placenta, 

 whilst the maternal portion is constituted by the ridges just described. 

 Underneath the marginal band of decidua reflexa, the foetal papillae 

 were of smaller size than elsewhere, and were arranged in tranverse 

 tortuous rows, which corresponded in breadth to that of the decidual 

 band. 



The foetal surface of the placenta, upon removal of the allantois, 

 was seen to be divided into numerous minute polygonal areas which 

 doubtless represent the so-called cotyledons described in the placenta 

 of other Carnivora. 



The placenta of the racoon presents no trace of the greenish 

 coloration met with in the margins of that organ in the case of the 

 bitch,* cat,f and fox.f Neither is it provided with any pigment- 

 containiiig sac similar to that described by Bischoff in the placenta of 

 Lutra,^ Martes,§ and Mustela.§ 



After removal of the placenta from the uterus, I attempted, by 

 means of a pipe inserted into one of the umbilical arteries, to inject 

 the foetal vessels. In consequence, however, of the parts having been 

 previously immersed in spirit, these were contracted to such an extent 

 as entirely to prevent the passage of the injecting fluid. To this 

 absence of injection was due the difficulty which I experienced in 

 obtaining a really satisfactory demonstration of the arrangement of 

 the placental blood-vessels in general, and more particularly of the 

 relation which the maternal vessels bear to those of the foetus. The 

 elucidation of this point will only be accomplished by the examination 

 of another injected specimen, but in view of the difficulty of obtain- 

 ing such, I think it advisable meanwhile to communicate the results of 

 my observations so far as they go. 



When sections were made of the placenta, and the uterine margins 

 of these were carefully examined under the higher powers of the micro- 



* Von Baer, TJntersuchungen." 



t Turner, " Lectures on the Comparative Anatomy of the Placenta," p. 71. 

 % " Sitzungsber. Akad. Wissensch.," Munchen, 11 Marz, 1865, p. 218. 

 § Ibid., 13 Mai, 1865, p. 339. 



